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The Reverse Osmosis Water Filter System: How Does it Work?

The reverse osmosis water filter is a system used to remove contaminants from water by sending water through a semipermeable membrane using pressure as the water moves from the higher concentration area with more contaminants of the Reverse Osmosis membrane to the low concentration area with fewer contaminants to get filtered, with the byproduct of the process being labeled brine. The inlet side of the RO membrane traps the impurities that flow into the central tube through the water channel before they flow out of the other end, separating clean water from the impurities and purifying it in the process. The natural osmotic pressure of water is the main driver of the RO process and the efficiency of an RO system in filtering/purifying water depends on the number of pre and post-filters it uses as well as the sophistication of the semipermeable membrane’s build as well as the proper maintenance and replacement of filters and the membrane. As long as the carbon and sediment filters remain operational and functional, meaning that the pores located in them are not blocked by accumulated contaminants and particles to result in low efficiencies of filtration/purification and that the semipermeable membrane also functions properly, the mentioned water pressure will continuously send unfiltered water through the system and the resultant water will be highly filtered for contaminants and dissolved substances, purified in the process, and will taste and smell food thanks to the final post-filter.    

The unique aspects of an RO system are that it does not consume any type of electricity but rather uses the naturally occurring water pressure to send unfiltered water through pre and post-filters as well as the semi-permeable membrane, while being able to be installed in numerous different settings for convenience and ease of use for the end-user, unlike other filtration systems that are quite bulky and occupy a lot of space, with questionable filtration/purification efficiency. These are also the advantages of using an RO system, namely its capability to work without any energy source, high levels of water filtration/purification efficiency, and ease of installation and use. The average cost of an RO system is $500-$2800 for home systems, $150-$1,300 for Point-of-Use TO systems, and $1,000-$20,000 for commercial systems.

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What is the Working Principle of a Reverse Osmosis Water Filter?

reverse osmosis water filter working principleThe working principle of Reverse Osmosis Water Filters depends on a membrane separation technique that utilizes pressure to drive water through a permeating and semipermeable membrane with the water molecules permeating the membrane when the applied pressure is greater than the osmotic pressure in the water solution. The mentioned semipermeable membrane has a porous structure consisting of small-sized pores and thus filters contaminants while allowing water to pass through, completing the first stage of the filtration process. 

The regular osmosis process further increases the concentration of water as it travels through the membrane and a certain equilibrium is reached on both sides but it is essentially the Reverse Osmosis process that stops contaminants from infiltrating into the low concentration area within the membrane, separating such contaminants from the original water source completely. Such contaminants include sediment and chlorine which are eliminated by a pre-filter located within the Reverse Osmosis system before water is sent through the semipermeable membrane to have the dissolved solids it contains removed and exits the membrane going through a post-filter and enters a faucet. Reverse Osmosis systems are categorized per the number of pre-filters and post-filters they use to treat water. 

Although the Reverse Osmosis membrane plays a critical role in the RO water filtration system, there are 3 to 5 filtration phases that utilize different filters with a sediment filter and a carbon filter being built-in parts of every RO water filtration system either as pre-filters or post-filters. A sediment filter is responsible for removing rust, dirt, and dust along with other unnatural particles found in water, a carbon filter filters out contaminants responsible for foul taste or smell in water, chemicals like chlorine, and organic compounds, while the semipermeable membrane filters total dissolved solids with an efficiency up to 98%. The carbon and sediment filters are generally used as pre-filters to protect the RO membrane against possible damages from sediment and chlorine, while the unharmed RO membrane filters out dissolved particles before sending the filtered water to a stored tank for later use with the system shutting off once the tank is full. A final post-filtration process is applied to filtered water awaiting in the storage tank when the water faucet is turned on to polish the drinking water before it hits the faucet.

A sufficiently efficient typical RO system consists of five different components, namely a pre-filter, a water softener, an RO treatment unit equipped with a storage tank and a flush, a carbon filter, and a post-treatment sub-micron filter, in the order which water passes through the system. The pre-filter is responsible for removing the larger-sized particles, debris, and rust, while the water softener removes calcium, magnesium in addition to other minerals from the water before replacing them with sodium or potassium, acting as a smaller diameter particle filter. The treatment unit holds the pressurized water in the storage tank before flushing it to the carbon filter which screens and filters the water for organic compounds, and the post-treatment filter applies the last process of filtration to the water on a submicron level to give the water a better texture and taste. 

In answering the question ‘How do Water Filters Work?’, the best approach is to consider the type of energy and the effectiveness of the filters used in the filtration process, as all water filtration systems utilize some type of energy to send unfiltered water through mechanisms of filtration and purification to produce higher quality water for the end-user. 

What are the Advantages of Using a Reverse Osmosis Water Filter?

The advantages of using a reverse osmosis water filter are listed below: 

  • Operational Efficiency: The first advantage of using a Reverse Osmosis Water Filter is the operational efficiency it offers in filtering water as the Reverse Osmosis process is capable of removing up to 98% of all contaminants found in water, which is an unmatched efficiency rate by other filtration systems like charcoal filters. The RO system generally applies three to five different stages of filtration as filters get finer towards the completion stage, making Reverse Osmosis a highly efficient water treatment system used in virtually every setting and procedure, ranging from large-scale wastewater treatment systems to basic drinking water filtration. As numerous minerals and almost all of the impurities are filtered out by the Reverse Osmosis process, using the resultant water for cooking offers more delicious food as the mentioned minerals and impurities change the taste of food. Most people boil ingredients before cooking to improve the taste of their food but the boiling process only removes bacteria found in water and not the contaminants, making the process highly inefficient in improving the taste of cooked food.
  • Cost: The RO process is energy efficient as Reverse Osmosis systems do not use electricity, as opposed to other systems like distillation that require electrical energy in the form of heat, as the only force required to operate the RO system is water pressure. This feature substantially lowers the costs of operation for an RO system and makes it a viable option for numerous customers. The Reverse Osmosis process also removes numerous minerals that are responsible for producing hard water, which is linked to various damages to plumbing systems. Although an RO system cannot replace a proper water softener, its highly efficient system of filtration will protect faucets and other hardware and when combined with a water softener, the results will be optimal. Water filtered through a Reverse Osmosis system is perfectly fine to drink and thus installing an RO system at home will create substantial cost reduction regarding drinking water, replacing costly bottled water with filtered tap water, saving substantial amounts of money for the user. 
  • Speed: An RO system connects directly to a faucet and provides clean water on demand, unlike a distillation system which requires substantial amounts of user input, such as manually refilling the water tank. The result is a highly speedy process that does not leave the end-user waiting for long periods, especially in tankless models, and provides highly filtered and purified water through a very short process that can be repeated at any given time granted that the RO system and its components are functional. 
  • Lifespan: An RO system, when properly installed, operated, and maintained, can last between 10 to 15 years in service, which is a very long lifespan for a home appliance, and therefore investing in an RO system makes perfect sense for end-users that seek to combine the availability of high-quality water with economic benefits when opting for clean, nutritious, and tasty drinking water. 
  • Maintenance: Apart from the carbon filters and the membrane, which need periodic replacements, an RO system is virtually costless to operate, meaning that maintenance takes place during such replacement operations, providing the end-user significant ease of use in between such operations. The sediment and carbon filters should be changed in periods of 6 to 12 months, while the final polishing/granular activated carbon (GAC) post-filter should be changed when a change or decrease in the taste of water has been observed, without a specified period having been established. The replacement of the RO membrane can be made every two to three years provided that the filters are replaced properly and periodically, which reduces the costs of maintenance. The system’s components should also be sanitized periodically, meaning that all the water should be disposed of through the faucet, all the dirt and dust getting cleaned, the main valve should be kept completely shut off, all the filters and the membrane should be removed from their housings, and the physical casing should be cleaned with hydrogen peroxide before all the connections are restored and the valves are turned back on and the system is operated without the filters for at least 2 cycles. Following this trial run, the main valve should be shut off one more time and the filters should be re-installed before the system can be properly operated with new filters and membranes one more time.

The most proper water treatment system to compare Reverse Osmosis with would be distillation as distilled water is at large considered to be a viable alternative to regular tap water or unfiltered water but when compared with RO system and RO filtered water, it is seen that distilled water lacks crucial elements that make it unpreferable for human consumption. The distillation process refers to the initial boiling of water to capture the condensation and then allowing the water to return to its liquid state to separate the impurities as well as to kill bacteria and microbes but the process will not remove certain chemicals, while the process’s excessive removal of minerals leads to a bland taste and lack of nutritional value. Similarly, water distillation creates far smaller quantities of water than needed by most people and therefore it does not make sense to use distilled water as drinking water. Distilled water is recommended generally for use in certain appliances such as steam irons, indoor aquariums, and laboratory experiments where mineral-free water is in demand. RO systems on the other hand produce excellent results for distilled water due to their high capabilities of eliminating contaminants, reserving water quality, taste, and odor, but more importantly, their far less sophisticated and far more economic mechanisms of water production.

What Types of Contaminants Does a Reverse Osmosis Water Filter Reduce?

An RO system will typically remove or substantially reduce the concentrations of contaminants found in the water by sending pressurized water through several pre and post-filters and a semipermeable membrane with pore sizes as low as 0.0001 microns to increase water quality, taste, and odor. The following list categorizes the contaminants, organisms, and compounds that RO systems reduce or eliminate efficiently to offer a comprehensive outlook on the system’s filtration/purification capabilities:

  • Ions and Metals: Aluminum, Calcium, Chromium, Fluoride, Copper, Cadmium, Arsenic, Chloride, Barium, Chloride, Lead, Chlorine, Magnesium, Mercury, Manganese, Iron, Potassium, Radon, Radium, Silver, Sulfate, Zinc, Sodium, Selenium, and Nitrate.
  • Organic Chemicals: Dichlorobenzene, Carbon, Tetrachloride, Toluene, Total Trihalomethanes (THMs), Trichloroethylene, and Benzene. 
  • Particles: Cryptosporidium, Protozoan Cysts, and Asbestos.
  • Pesticides: Atrazine, Heptachlor, Pentachlorophenol, Endrin, 2,4-D, Lindane, and 1,2,4-trichlorobenzene.
  • Bacteria, Protozoa, and Viruses: Giardia, Cryptosporidium, Salmonella, Escherichia Coli, Campylobacter, Shigella, rotavirus, Enteric, Norovirus, and Hepatitis A.  

The contaminants not removed from water by reverse osmosis include dissolved gases like hydrogen sulfide, pesticide not mentioned in the previous paragraph, most herbicides, and fungicides, while the average RO system also has a high chance of not removing all the chlorine present in water, depending on the concentration of the chemical in the water during the process of water purification.

Does a Reverse Osmosis Water Filter System Purify the Water?

Yes, a Reverse Osmosis Water Filter System does purify water as the water is sent through the semipermeable membrane where the above-mentioned contaminants are removed and the water is sent to the post-treatment filter to be polished before it is sent to the faucet. These two stages both purify water before it reaches the end-user. 

Does the Reverse Osmosis Water Filter System Remove Bacteria in Water?

Yes, the Reverse Osmosis water filter system removes bacteria. An RO membrane with a pore size of 0.0001 microns, is highly effective in removing certain types of protozoa like Giardia and Cryptosporidium, while also showing high effectiveness against bacteria like Escherichia Coli, Salmonella, Campylobacter, and Shigella. As for viruses, the RO system also shows high effectiveness against Hepatitis A, Rotavirus, Norovirus, and Enteric.  

Does a Reverse Osmosis Water Filter System Remove the Chemicals in Water?

Yes, an RO system successfully removes common chemical contaminants that exist in the forms of metal ions and aqueous salts like chloride, chromium, lead, copper, and sodium, while substantially reducing the concentrations of other contaminants like calcium, phosphorus, nitrate, magnesium, potassium, sulfate, fluoride, arsenic, and radium. 

Does a Reverse Osmosis Water Filter System Affect the PH of Water?

The Reverse Osmosis process generates acidic water, meaning that RO water has a lower pH level than regular water. pH for water is a highly important parameter for water because it is directly related to its composition, quality, and potential to house different materials and compounds. In its natural state, reverse osmosis water is almost pure water having a pH level of 7 as 99% of the contaminants in water are removed through several filtration stages. However, it has also been observed and reported that RO water drops to a pH range of 5 – 5.5 and becomes acidic after the treatment, which is due to exposure to air. The newly filtered water is a CO2 magnet and its pH level can drop to lower levels, specifically from 7 to around 5.5, within an hour following the RO filtering process making the water acidic. Although natural water found in lakes, seas, streams, and rivers also undergo a similar process, pure water produced by the Reverse Osmosis and distillation processes can absorb far more CO2 than regular water, which is why the mentioned phenomenon of acidity is observed in RO water.

How to Configure a Reverse Osmosis (RO) Water Filter System?

A Reverse Osmosis Water Filter System consists of an RO module, an angle stop valve, two or three pre-filters, an automatic shut-off valve, a membrane, a post-filter, a bladder tank, a drinking water faucet, a drain clamp, several tubing parts, and quick-connect fittings. 

The reverse osmosis water filtration system can be installed under a sink or in a basement where it will not be exposed to extremely low temperatures during the winter with the faucet being mounted on a 2” flat surface equipped with a hole and a thickness of no more than 1-¼”, while the bladder tank should be placed within ten feet of the faucet in a lower level within secure shelving, given the weight of the component. The RO unit should be mounted on either side of the installation or placed under it for ease of access for future maintenance, while an angle stop valve designed to supply water to the RO unit should be located as close to the installation as possible to connect the upper part of the cold water shut-off valve and the bottom part of the riser tube between the cold water shut-off mechanism and the faucet. The drain saddle fits with a standard 1-½” OD drainpipe to connect water with the drain and should be above the p-trap either vertically or horizontally. After the installation location is chosen according to the given provisions, the cold water valve should be closed before the cold water line is connected to the unit, following which the drain line should be connected and the faucet should be installed. 

The possible mistakes made during the installation of an RO system include installation of the RO system in an incorrect spot where the system experiences high variations in temperature resulting in irregular feed water temperature, improper choice of feed water that might not be suitable for the RO system with high concentrations of Iron, organic matter and free chlorine as well as high levels of water hardness, that is highly damaging to RO membranes. Inadequate RO feed water pretreatment is a common issue in RO installations that results in degradation of equipment and the quality of water. Similarly, the lack of individual flow meters installed on every filter placed parallel to each other makes it impossible to know about the balance of the flow rates and thus the regime of the water flow.

Another common mistake is injecting polymeric filtration aid onto the media filters which leads to the accumulation of polymers that cause serious damage to the filter as the polymer permanently bonds with the RO membrane and attracts numerous types of suspended solids that are normally expected to migrate along the membrane surface. The RO fouling rate will increase and the overall system performance will be lowered until the membrane is replaced or an inorganic coagulant like aluminum or ferric chloride should be used to send particles upstream. Scale formation is also a common issue observed in RO systems and not using a chemical scale inhibitor that binds with growing scale crystals to reduce their particle growth rate is a mistake that should be avoided. Another critical mistake made when installing an RO system is the lack of monitoring regarding the RO membrane elements by observing the accurate water flow rate and pressure readings, for which flow transducers and meters are necessary to install to monitor both the upstream and downstream flows. Using an automatic isolation valve or a vacuum breaking valve is also recommended to control the water flow efficiently as a siphon-based system is likely to create leakages and other similar issues for the RO system. Similarly, specialty gaskets should be used to maintain efficient sealing under vacuum conditions as Victaulic-style couplings allow water to drain from RO pressure vessels while standard gaskets allow air to enter the RO system to displace the exiting water. When such leakages and air-intakes occur, bacteria and fungi spores will grow within the membrane elements and corrode them, with a high possibility of the water hammer effect taking place during the process as well. To prevent unnecessary air intake, a check valve that operates on a 1-2 PSI pressured spring should be placed on the concentrate discharge route to allow air to be discharged into the line when the system is under vacuum conditions.

What are the Configuration Types of Reverse Osmosis Water Filter Systems?

Mainly, there are three configuration types of Reverse Osmosis water filter systems. The configuration types of Reverse Osmosis water filter systems are quick-change filter cartridges, drop-in filter cartridges, and standard filter cartridges. The configurations can change by the type of water filter cartridge being used in the system. 

1. Quick-change Filter Cartridges

Quick-change filter cartridges are a self-encapsulated filter system consisting of several membranes that can be easily removed or replaced with the internal valve shutting the water flow automatically when one of the cartridges is removed. Quick-change filter cartridge efficiency levels range as high as 99% to eliminate contaminants, the system is easy to replace with a simple ¼ turn, does not require tubing to be disconnected when the membranes are replaced, has hinged bracket aids to uphold the cartridges for easy replacement, leak-proof thanks to its cartridges that come with double o-rings, houses several valves to prevent back-flow of water, can be used to supply water to a refrigerator, an ice-maker, or a water dispenser, and houses automatic shut-off valves to eliminate water waste by shutting off the feed line when the storage tank is full. The quick-change filter cartridge system consists of a faucet, a storage tank, and usually four different cartridges that filter water in four different stages. In the first stage, first, rust, and other suspended particles are removed, in the second stage, chlorine, taste, and odor are removed, in the third stage, the RO membrane removes dissolved solid with an efficiency of up to 99%, and in the fourth and final stage, the post-filter polishes the water for taste and odor.

2. Drop-in Filter Cartridges

Drop-in Filter Cartridges are generally used within water filter housings and come in a standard size of 2.5 inches in diameter to eliminate sediment down to a 5-micron nominal level. The diameter size can be increased to 20 inches, while the built-in carbon block reduces the concentration of chlorine in water and removes odor, with the more advanced models having a built-in scale inhibitor that reduces the physical harm that the filter can endure due to scale build-up over long periods. Generally manufactured using polypropylene, the drop-in filter cartridges are an excellent solution to sediment accumulation due to water pressure variations, while requiring periodic maintenance for optimal performance. Drop-in filter cartridges have a grooved surface that increases the total surface area used in the process and prolongs service life, with the average service life being 6 months, depending on water quality. (Home Depot, 2021) (3M, 2021)

3. Standard Filter Cartridges

The standard set of RO filter cartridges includes a sediment filter, a granular activated carbon filter, a carbon block filter, and a post-carbon filter. The sediment filter acts as the first barrier within the RO system and removes solid particles like dirt, silt, and rust from the unfiltered water to provide the initial stage of contaminant elimination. Through such filtration, it prevents the remaining filters from getting clogged with large-sized particles and thus reduces the chances of potential damages to the filters, commonly coming in a 5-micron size. The granular activated carbon filter removes impurities to prolong the service life of the membrane while trapping and absorbing organic chemicals and chlorine in the mildly filtered water through mechanical filtration and physical absorption. The process also removes odors from the water and improves its taste. The carbon block filter applies the same procedures with more intensity thanks to its smaller pore sizes, while the post-carbon filter acts as the final stage of filtration in the RO system to trap any particles that might have accumulated in the tank before the water becomes accessible through a faucet. The average service life of the mentioned filters is around 12 months, depending on the quality of water and the amount of usage. 

What is a Reverse Osmosis Faucet?

configuration of a reverse osmosis water filter systemA Reverse Osmosis faucet is a fixture placed on a sink or a basin to store or drain water with the function of drawing or regulating the flow of water from the feeder pipe that extends from the storage tank in RO systems with a tank or directly from the RO unit in tankless RO systems. Most RO systems come with a special air-gap faucet, while most manufacturers offer a non-air gap option as well. An air-gap faucet operates just like a non-air gap faucet in dispensing water while having an air gap present in the base of the faucet to prevent backflow into the RO unit. 

In the case of clogging, a small amount of air goes back into the RO unit instead of dirty water to protect the system. Due to the highly fine nature of the RO filtration process, all RO systems allow some water to the drain, with the RO membrane continuously washing itself off and sending impurities to the drain to preserve the water quality. An air-gap faucet creates a physical siphon break in the RO system and the sink drain by releasing water from one of its tubes into the other using air pressure. An air-gap system sends the drain water upwards using a ¼” flexible tube to a small-sized feeder that is housed in the base of the faucet, allowing water to flow from the feeder to the other section of the faucet stem before entering a hole and dripping into a ” flexible tube with the force of gravity and reaching the drainpipe located under the sink. To carry out this process, the air-gap faucet is designed to house three tubes to push the drain water upwards and downwards as well as allowing the RO system’s product water to pass through for the consumption of the end-user, while a wider base for the air-gap faucet and a larger hole in the sink are also necessities. 

The main difference between an air-gap and non-air gap faucet is that in a non-air gap faucet, the drain water from the RO membrane is directly sent to the sink drain, having only the drinking water line connected to it. The advantage of an air-gap faucet is the physical protection it offers for the RO system as a possible backflow into the RO system substantially damages the physical parts of the unit and contaminates the RO membrane. The disadvantages of an air-gap faucet are sediment clogging that results in water accumulation in the sink or countertops, the extra gurgling noise that it creates as the storage tank is filled up, and the difficulties of installation that requires extra tubing and connections. A non-air gap faucet on the other hand has the advantages of lower cost, ease of installation with fewer tubings and hoses, and less noise, and the disadvantage of potential damage to the RO system and the RO membrane in cases of clogging

What is a Reverse Osmosis Undersink Water Filter?

A Reverse Osmosis under sink water filter is any of the five or more recommended filters used in an RO system with the unit being placed under the sink to be close to the water source and have adequate space for the storage tank. The main advantage of an under-sink RO system is that due to the lack of space constraints for installation, the system can be larger to have more capacity than countertop models which are designed to be as compact as possible to fit in with kitchens. An under-sink RO system can operate with or without a tank as the only difference it has compared to countertop models is its size and its location, without any functional difference. To locate and purchase the best under sink water filters, it is necessary to do substantial amounts of research and consulting, while it should be noted that all the major RO system manufacturers, such as Aquaphor, APEC, iSpring, NU Aqua, Waterdrop, Frizzlife, Express Water, Home Master, and RKIN, AquaPure, Brondell, Global Water, Hydrotech, PurePro, Vitev, and Watts, with the average price range for under-sink RO systems being $300-$600 for tankless models and $200-$600 for models with a tank.   

What is the Average Cost of a Reverse Osmosis Water Filter System?

The average cost of a Reverse Osmosis water filter system is between $150 and $3000. Commonly available Reverse Osmosis Water Filter Systems by manufacturers, such as Aquaphor, APEC, iSpring, NU Aqua, Waterdrop, Frizzlife, Express Water, Home Master, and RKIN, AquaPure, Brondell, Global Water, Hydrotech, PurePro, Vitev, and Watts cost between $500 and $2,800 for whole-home RO systems, $150 to $1,300 for Point of Use RO systems, and $1,000 to $20,000+ for commercial-grade systems.

What is the Reverse Osmosis Water Filter Price Factors?

The main cost/price factors for RO systems and filters are size, filtration process, NSF certifications, brand, additional features, and labor costs. The RO products market is quite vivid, enabling the consumers to locate and purchase a variety of different systems, ranging from the most expensive RO systems and products to the most affordable water filters. All the previously manufacturers, namely Aquaphor, APEC, iSpring, NU Aqua, Waterdrop, Frizzlife, Express Water, Home Master, and RKIN, AquaPure, Brondell, Global Water, Hydrotech, PurePro, Vitev, and Watts, offer a variety of different models and products at varying price levels and therefore it is essential to pay attention to the mentioned price factors when reaching a decision on which RO system to purchase from which manufacturer. 

  • Size: The size of an RO system is important because with size increments come sophistication in design and function for the RO system, while size also determines the location of the RO system and how much space it will occupy, which are both important determinants for an RO system’s value for the customer.
  • Filtration Process: Filtration is an important stage in an RO system’s operations because more sophisticated systems that use even UV light to kill pathogens cost more due to the higher number of technical parts involved in their operational processes. 
  • NSF Certifications: These certifications signify an RO system’s capability to reduce or eliminate one or more types of contaminants with the most important NSF standards for RO systems being 42,53,58, 401, and P473. As more certificates are granted to an RO system to signify higher operational efficiency, the price of the unit goes up. 
  • Brand Value: This value is important in the RO systems market with certain brands that incorporate higher quality materials and design in their products offering higher-priced products to the market. 
  • Additional Features: Different RO systems have various additional features such as the use of a specialized pump to increase water pressure and therefore water production capacity and efficiency, as well as the amount of water flow and decrease the amount of wastewater going down the drain. Additionally, certain systems also have add-ons such as extra re-mineralization stages to balance the pH level of the water and increase water alkalinity, as well as a modular design that offers practicality in replacing filters and the membrane and protection against germ accumulation in the system. 
  • Labor Costs: Labor costs involved in installing an RO system are costs of basic labor, referring to mounting the RO faucet and the RO module, installing the drain saddle, connecting the system to the water source, filter and RO membrane installation, system initiation, operational controls, and the physical clean up, the costs of the required supplies, namely connectors, fittings, and adapters, and costs of equipment to be used in the installation process, such as screwdrivers, tubing cutters, utility knives, dill bits, and adjustable wrenches.

What are the Unique Aspects of a Reverse Osmosis Water Filter?

Although an RO system operates similarly to other systems of water filtration/purification on a basic level, there are certain unique aspects of the RO process that deserve recognition.

  • Filtration at the micro-level: When compared with ordinary water filters that physically screen dirt and sediment down to around one micron without removing dissolved chemicals, an RO water filter filters down to the molecular level using a polymer membrane and removes dissolved chemicals and salts along with dirt and sediment. 
  • High service quality due to surface wide operation on the RO membrane: Unlike regular filters that allow the water the flow through the filters while trapping the particles in the filter or on its surface, an RO water filter allows the feed water to flow across the membrane surface while the purified water goes through the membrane, offering higher levels of elimination for the impurities into the drain, continuously keeping the RO membrane contaminant-free, extending the service life of the RO membrane, and ensuring high levels of purity for the filtered water. 
  • Different types of use, including Desalination: Reverse Osmosis water filtration technology can be used to desalinate seawater to deal with water shortages in regions with water scarcity, as with 44% of usable water in the Middle East and North Africa being supplied by desalination plants running on RO systems. 
  • High efficiency in water filtration: An RO water filter also filters out most contaminants found in water with an efficiency of 95% for fluoride and mercury, 97% for chlorine and arsenic, and 99% for lead and asbestos along with 82 other contaminants. Such high efficiencies of filtration produce perfect results in providing pure drinking water that is free of bacteria, contaminants, and heavy metals, while the RO process is perfectly capable of filtering extremely high mineral content with a TDS of 1500 or higher to make it drinkable. 
  • Alternative to bottled water, cost efficiency: RO filtered water is also a viable alternative to bottled water because it can be consumed without being bottled in a plastic bottle and the lack of regulation in the bottled water industry poses serious health risks for the consumers of bottled water. 
  • RO water is ideal for cooking: In addition, numerous restaurants use reverse osmosis water to wash ingredients and cook for better tasting food as RO water offers complete hygiene for ingredients as well as the perfect canvas to cook due to the lack of certain taste-altering contaminants. 
  • No chemical additives: It should also be noted that the RO filtration process does not require any chemical additives as the process only filters out dissolved substances from the water intake.     

How to Install a Reverse Osmosis Water Filter?

reverse osmosis system installation guideThe installation process of a Reverse Osmosis Water Filter takes place in 9 different steps that all focus on different components and their proper placement within the space they occupy and the unit itself. In this respect how to install a Reverse Osmosis water filter system is not a very simple process. These steps, in consecutive order, are the installation of the faucet, the mounting of the faucet, the installation of the angle stop valve and tubing, the installation of the drain saddle valve, establishing the initial tubing connections, the installation of the RO component, the installation of the RO unit, the pre-filling process and the placement of the supply tank, as well as finalizing the tubing connections. 

In the first step to installing the faucet, if the sink has a sprayer, it should be disconnected and a faucet-mounting hole should be drilled over a 2-inch flat surface with a thickness of 1-¼” inches with the faucet positioned properly to allow the water to be emptied into the sink directly. Special care should be paid to drilling holes in sinks made of porcelain, ceramic on metal, cast iron, enamel to penetrate the material properly without damaging the unit while proper equipment should be used to drill through stainless steel sinks. In the second step when mounting the faucet, the hardware should be disassembled from its shank using the chrome base plates and rubber washes and the shank should be placed within the sinkhole so that the faucet can be oriented. Consequently, the slide lock washer and the hex nut placed on the shank should be slid from below the sink and tightened using a wrench. When installing the angle stop valve and the tubing in the third step, the cold water supply should be turned off by using the angle stop shut-off mechanism under the sink, and pressure should be relieved by turning on the cold water faucet after the valve is shut off. Next, the rise tube should be disconnected from the cold water shutting off mechanism with a wrench and the tubing should be moved away from the valve to create space for the Angle Stop Valve. After lightly connecting the swivel end of the valve to the threads on the cold water shut-off mechanism, the riser tube should be connected to the male end of the valve and tightened with a wrench. Finally, tubing with a length of ¼” should be connected between the valve and the RO unit’s inlet.       

When installing the drain saddle valve in the fourth step, the valve should be positioned at a precise location marked for the opening hole and a ¼” hole should be drilled at the marked spot going through on the side of the pipe. Next, the backing from the gasket should be removed and its adhesive side should be placed on the adhesive side of the drain clamp that fits around the drilled hole with both halves of the saddle being positioned on the drainpipe in a way that the opening aligns directly with the hole. The drain saddle clamp should then be secured on the valve with the provided bolts and nuts. After the initial tubing connections are established for under-sink installations, the sediment cartridge, the reverse osmosis membrane, and carbon block cartridges provided in the packaging should be installed to complete the RO unit. The polypropylene sediment cartridge should be installed first on the inlet end, followed by the carbon block cartridge with either end being installed first while the membrane finds its place in the membrane housing unit with its o-ring end being installed first. When installing the RO unit, it is important to mount it on the right or left sidewall to the sink cabinet in line with the position of the supply tank, with the most common location being in front of the cabinet and the storage tank in the back. The unit should stand at least 2” above the ground level, with the mounting holes marked and the unit is secured with mounting screws and install screws while allowing the mounting bracket slots to slide over the unit. In the eighth step when placing the pre-fill and supply tanks, adequate pressure should be generated by pre-filling the storage tank to control the unit for leaks as well as sufficient water to flush the carbon filter. The feed line that supplies the RO unit should be connected to the bladder tank and water should be allowed to fill the tank until its maximum capacity. Following these steps, the feed pressure should be shut off, the reducer tube should be released and the reducer should be removed from the tank valve, while the supply tank should be positioned under the counter or within 10 feet of proximity to the RO unit. In the final step of completing the tubing connections, the contour of the cabinets should be followed by tubing for which it is necessary to cut certain parts of tubing to the proper length with a cutting tool and no crimps should be left behind in the tubing area. To sustain a desirable level of flow, the tubing extending from the RO unit to the storage tank and the faucet should be kept as short as possible, while the drain flow restrictor on the drain line where the drain line and the RO unit connect should not be removed.           

What are the Components of a Reverse Osmosis Water Filter?

A Reverse Osmosis Water Filter system has numerous components for filtering, storage, and transportation of water. The components of a Reverse Osmosis water filter are listed below:   

  • Water Supply Connector/Feed Water Supply Adapter: This component provides the main source of unfiltered and unpurified water to the RO system by connecting to the main cold water supply available in the location of the RO system’s installation and is used with an adapter to work with a variety of different supply systems. 
  • The Sediment Pre-filter: The component houses a sediment cartridge that eliminates large-sized particles such as grit, sand, insoluble iron oxide, debris, and mineral residue from the fresh intake of unfiltered water to protect the RO membrane surface from clogging and the drain flow restrictor from getting blocked leading to lower levels of water production. Most sediment filters contaminants at a 5-micron level and should be replaced every six months for optimal operation and three months if the filter is smaller in size. 
  • The Carbon Filter to Remove Chlorine: This filter eliminates excessive concentrations of chlorine, which is added to water sources by city utilities to prevent harmful bacteria, virus, and microorganism growth, which is a prime cause for numerous serious illnesses and also deteriorate Thin-film Composite Membranes (TFCs). Generally, most available city water utilities necessitate a minimum chlorine level of 1.0 mg per liter, or 1.0 ppm, which leads the RO membrane to reject fewer amounts of contaminants and higher amounts of Totally Dissolved Solids (TDSs) to pass through. This specific carbon filter eliminates a large percentage of the mentioned chlorine and thus protects the RO membrane through which the high-chlorine water would otherwise pass through. 
  • Carbon Filter to Remove Chloramine: This filter plays an important role in maintaining proper levels of filtration because studies have shown that consuming products containing chlorine disinfection byproducts is linked to a higher risk of cancer. Although an RO membrane can withstand higher chloramine concentrations of 1 to 2 ppm without experiencing any damage, the catalyst effect of metals found in water like aluminum and iron leads to faster oxidation of the membrane even at low levels of chloramine concentration, leading to inefficient chloramine filtration due to lower levels of salt rejection. This is why a stronger carbon filter is needed because the contact time for effective removal of chloramine is five times longer than the contact time for chlorine removal, which can only be provided with high amounts of activated carbon through a special carbon filter.  
  • The Auto Shut-off Valve/ASO Control Valve: The valve controls the water supply that enters the reverse osmosis membrane and stops the drain flow when the storage tank reaches of the feed water pressure to save water and turns the water back on when the water level in the tank falls to of the feed pressure. 
  • Reverse Osmosis Membrane: Being the most crucial component in an RO system, the RO membrane eliminates up to 96% of all TDS, namely minerals, metals, and salts, as well as organic substances and microorganisms in the incoming water. To accomplish this feature, the membrane creates two streams of water flow with the filtered water going into the storage tank and the contaminated water going into the drain with most RO systems generating around four gallons of wastewater for every one gallon of filtered/purified water when operating in an urban water supply with above 70 PSI water pressure, with the given 4-to-1 ratio being regulated by the flow restrictor positioned on the drain line. 
  • The Check Valve: This valve’s function in an RO unit is to prevent pressurized water stored in the tank from flowing back into the membrane and damaging it as the feed water pressure is cut off by the ASO valve. 
  • The Post-Carbon Inline Filter: This filter is where the remnants of any tastes or odors are eliminated from the filtered/purified water with a substantially higher contact time due to the slow flow of water through the filter, allowing for higher rates of absorption effectiveness to be achieved. 
  • The Pressurized Water Storage Tank: The tank provides the necessary pressurized water when the faucet is turned on with the filtered water permeating from the membrane, containing a bladder positioned in a metal or plastic case to separate the water chamber from the compressed air. The bladder expands to compress the air enclosed within the casing as the RO water fills the tank and when the faucet is turned on, the pressurized air pushes the water out with the under-sink RO systems housing an empty water storage tank with 5-7 PSI of air charge. When the air charge is increased the volume of stored water will decrease and the lower air pressure in the empty tank will create a lower flow rate for the water that flows through the faucet and therefore it is advised that the end-user makes the appropriate adjustments for optimal performance. 
  • Drinking-Water Faucet: An RO system usually comes with a non-air gap water faucet that requires no installation but if an air gap faucet needs to be installed, additional drain line connections need to be established to protect the RO system against issues like reserve suction. 
  • Optional Components: The optional Pressure Regulator protects the pre-filter housings against high pressure and the water hammer effect as the maximum pressure rating of 75 PSI for the standard housing units is considered to be ineffective against the mentioned issues. The other mentioned option RO components also have their specific functions for either certain other components within the system or the system as a whole, and thus are recommended for specific types of use.                   

What is the Reverse Osmosis Accessories?

Some of the most common and recommended Reverse osmosis accessories are a TDS Meter, a Water Filter Sanitising Kit, an Alkaline Water Filter Cartridge, and a Reverse Osmosis Booster Pump. 

  • A TDS Meter: The accessory measures the level of TDS in water to determine the usability of the RO membrane and the pre and post-filter cartridges. TDS are the dissolved minerals, metals, anions, cations, and salts in water and higher TDS levels signify higher levels of contamination in the water, making a TDS Meter a highly reasonable accessory to be used with an RO system. 
  • A Water Filter Sanitising Kit: The kit is a highly useful accessory that helps the end-user clear debris or dirt build-up in the RO storage tank that might otherwise cause taste and odor in the stored water. 
  • An Alkaline Water Filter Cartridge: The cartridge can be used to bring down the acidity of tap water by adding slight amounts of minerals to the water to increase its pH level, as RO systems have been known to strip down the healthy minerals out of the water they filter along with harmful contaminants, in turn making the filtered water slightly acidic. 
  • A Reverse Osmosis Booster Pump: The RO booster pump is a preferable accessory to use with an RO system in cases where the water intake has a lower level of water pressure than the required level, reducing the performance of the RO system to make it produce more contaminated water and less filtered/purified water for which the water pressure boosting capabilities of a Reverse Osmosis Booster Pump are a direct solution.

What are the Possible Problems for Reverse Osmosis Water Filter Systems?

Some of the most common possible problems for Reverse Osmosis Water Systems are a noisy faucet or drain in the system, leaking in the faucet, unpleasant odor or bad smell in water, system running non-stop, slow water flow, and the RO water tank not filling. 

  • Noisy Faucet/Drain in the RO System: The first problem refers to cases where an unnatural noise is heard coming from the system as a result of air being pushed out when the system has either been newly installed or the filter cartridges have been changed. 
  • Faucet Leakage: This issue refers to the faucet running water even if it is shut off, causing not only economic damage due to continuous water flow but also damage to the components of the RO system. 
  • Unpleasant Odor or Bad Smell: These are significant issues that need immediate attention because they signify technical problems and due to these issues, the water quality is substantially lower than anticipated. 
  • A Non-stop Running RO System: The problem refers to the RO system not being properly shut off even after it is switched off manually, signifying both technical issues and creating economic problems due to continuous energy consumption. 
  • Slow Water Flow: When the water is flowing slower than expected, it creates problems for the end-user and signifies technical problems that need to be addressed immediately as otherwise, the overall efficiency of the system will remain below the required levels. 
  • RO Water Tank Not Filling: When an RO water tank does not fill up properly, the efficiency of the system is substantially lower than usual and such inefficiency creates problems for the end-user, not to mention possible damages to the components of the system in the long term. 

The most common problem for an RO system is a noisy faucet/drain because it is quite easy for an RO system to develop issues with air that circulates within the system as the RO process operates using water pressure, which pushes all matter in the system, including air. Given the highly integrated nature of the mechanism, it is also quite possible for such air to be stuck in certain parts or overload certain mechanisms to create technical issues, with the faucet being one of such parts due to its final position in the system where the treated and pressurized water meets the end-user.  

How to Repair a Reverse Osmosis Water Filter?

Much like any other integrated mechanical system, an RO Water Filtration system also endures malfunctions and requires repair and maintenance for proper operation and optimal results. The question ‘How to Repair a Reverse Osmosis Water Filter System?’ has many answers in line with the different types of components involved in cases of malfunction and the different types of problems/symptoms observed that require different technical methods and approaches for proper results. 

One possible solution for a noisy faucet or drain is to check the tubing and make sure they are all properly connected and operating, while it has been noted that the given sound usually gradually reduces and disappears within a week of installation.

When the faucet is leaking, it is a solid sign that certain system parts have been fitted loosely and it is necessary to locate the origin of the leakage because if it has originated from the bottom end of the faucet, the fittings can be tightened and the tubing can be pushed further towards the valves and the drain saddle to fix the problem.

In the case of foul odor or a bad taste in water, it is necessary to check the storage water for stagnant water which is at large the main source of foul odor, and the depleted filter and worn-out membranes which are the main reason for bad taste in water. Changing the mentioned faulty components will fix the bad taste issue and changing the storage water periodically will solve the foul smell issue.

A non-stop running RO System is usually due to a non-properly closed shut-off valve or a broken check valve, while an improperly installed membrane also causes continuous system operation. As remedies, the storage tank pressure needs to be measured to make sure that the value reads between 35 and 40 PSI, and in case the check valve is not working properly, it should be replaced.

When the water is flowing slower than expected in an RO system, it is a sign of water pressure and volume for which it is necessary to check the storage tank pressure and increase it to 6 to 8 PSI with a pressure gauge if the original level is lower than required. In the case of the tank bladder not being able to sustain the necessary pressure level, then the entire tank unit should be replaced. 

In cases where the RO water tank does not fill up properly, the problem is mainly due to extremely low water pressure in the RO system, with the required pressure level being between 40 and 60 PSI for optimal operation. In such cases, a water pump should be used to increase the water pressure in the RO system. Another reason for the water tank not getting filled properly is a faulty RO membrane as an improperly functioning membrane does not allow the required amount of water to pass through and thus needs to be replaced.   

What is the Maintenance Cost of a Reverse Osmosis Water Filter System?

The maintenance cost of a Reverse Osmosis water filter system is roughly $150 to $800 on average annually.  While there are no significant operational costs for RO systems, there are costs of replacement for filters and membranes with the frequency of such replacements changing per levels of water consumption and feed water quality, as issues such as high levels of chlorine and water hardness reduce the service life of these components substantially. As a general rule of thumb, it is recommended that the filters should be changed every 6 or 12 months depending on their build quality, while RO membranes can last up to 3 to 5 years. 

The costs of replacement of filters and membranes increase with more filtration stages being employed in the RO system but on average, the annual costs of replacement range between $60 to $200 while replacing filters in a modular design system costing more due to the need to dispose of the entire housing for the filters and membranes. 

The extra costs of wastewater are only relevant in high-volume applications, such as whole-house systems that have a bare minimum recovery rate of 33%, or 2:1, meaning that two extra gallons of wastewater are produced for every gallon of purified water. 

As a viable solution, it is recommended to use a pressurized pump, a recycle valve, and multi-membrane units, as the combined utilization of these components increases the recovery rate up to 75%, equating to one extra gallon of wastewater for every three gallons of purified water.

What is the Lifespan of a Reverse Osmosis Water Filter System?

The lifespan of a Reverse Osmosis water filter system is between 10 to 15 years granted that they are regularly inspected and maintained. This means that the filter cartridges and the membrane should be replaced at least once a year and once every two years respectively. The other components like water storage tanks, piping, fittings, housing. and tubing should also be inspected against issues related to air and moisture and be replaced if found to be defective.  

Who Invented the Reverse Osmosis Water Filter System?

The history of artificial Reverse Osmosis systems begins in 1748 when a French physicist, Jean-Antoine Nollet, discovered the process by replicating the osmotic process in an experiment where he used a pig bladder as a semipermeable membrane and passed solvent molecules from a low-solute water source to a higher-solute concentration of alcohol, proving that solvents could pass through and be filtered through a semipermeable membrane using natural osmotic pressure until the dynamic equilibrium is reached in both sides. In the 1940s, American universities furthered Nollet’s studies in their attempts to filter or desalinate seawater, and in 1959, two UCLA researchers, Sidney Loeb and Srinivasa Sourirajan produced a synthetic RO membrane using cellulose acetate polymer, sending pressured high-solute water through it and succeeded in separating water molecules from NaCl (salt) and TDS. This technology soon was applied to freshwater soon after the initial experiment to produce filtered, purified, and drinkable water and because the technology reversed the natural osmotic process, it was after the initial experiment when the wording ‘reverse osmosis’ was used to define the process. The first commercial RO plant was constructed in 1965 in Coalinga, California under the supervision of Joseph W. McCutchan and Sidney Loeb with numerous guest engineers and government officials from different parts of the world to desalinate seawater. Following the establishment of the plant, RO systems and the technologies they used began to become mainstream and as they became less expensive and more available in the markets, residential models began to be built. 

What Type of Membrane Does the RO Water Filter Use?

The type of membrane that an RO water filter uses is a semipermeable one. The semipermeable membrane used in the RO process is usually made of two layers: a thin polyimide layer with a thickness of <200 nm placed on top of a polysulfone porous layer with a thickness of 50 microns located on top of a non-woven fabric sheet, with an average pore size being 0.0001 microns to allow water molecules to pass through and exclude most dissolved contaminants. For residential and commercial setups, these water treatment membranes can have a two-to-eight inches diameter size and for industrial applications, the size has been established as forty inches.

What is the Importance of a Tank for a Reverse Osmosis Water Filter?

The ability to store water for future use is a certain privilege that many home and office owners enjoy, which is why they choose RO systems that come with a built-in storage tank. In addition to this obvious advantage, Reverse Osmosis tanks operate using high pressure, which is a highly important element in an RO system’s operation because it is the driving force for all water transfer and filtration in the system. The two functions of the storage tank in an RO system that make it essential are providing pressurized water for the use of the end-user and maintaining pressure throughout the system and monitoring the line pressure to actuate the on and off circles of the system. The built-in sensory valve in the RO system stops water production when the tank pressure reaches of the line pressure by moving the shut-off valve to the closed position while filling the tank under 60 PSI of feed pressure and compressing air when the feed pressure drops to 40 PSI. This collaborative functionality of the automatic shut-off valves and the storage tank is crucial for the system as it protects the system against possible overloading issues which would damage the RO membrane as the excess water would otherwise be directly sent to the membrane, saving large quantities of water for the end-user. 

What is the Advantage of a Tankless Reverse Osmosis Water Filter?

The advantages of a Tankless Reverse Osmosis Filter System are its compactness, as the system occupies far less space compared to an RO system with a tank, its use of multiple membranes to offer higher efficiency in filtering water, the instant access it offers to water as no time is required for water to accumulate in a tank, the better-tasting water it produces compared to stored water, its economic benefits as water is produced only when the end-user runs the system and the less amount of wastewater it produces when compared to traditional RO systems.

What Are the Differences Between Distilled Water and Reverse Osmosis Water?

Although water distillation and reverse osmosis filtration are both highly popular options among water consumers that seek to increase the quality and hygiene of the water they produce, there are substantial differences that need to be accounted for in terms of the methodologies they employ and the results they produce.

  • The Water Distillation Process: Distilled Water is produced through the water distillation process which is the boiling of water into steam to remove all impurities and contaminants and the recollection of the boiled water in a condenser to be cooled off, following which, the water returns to its liquid state before being sent through a carbon post-filter to remove any remaining chemicals. The result is completely pure water with a dissolved solid ratio of one in one million that is completely safe to drink but lacks essential minerals, has a bland taste, and requires long periods to produce. 
  • The Reverse Osmosis Water Filtration Process: Reverse osmosis water is produced with water being pushed through a semipermeable membrane with high pressure to remove all impurities and contaminants in the water at microscopic levels before the water is sent through several filters to remove remaining substances in the water and a final mineral filter where essential minerals are added back in the water to make the resultant water more nutritious and tastier. The only disadvantage of RO water is that the process to produce it can be more expensive than most other filtration systems.  

Does a Reverse Osmosis Water Filter Generate Alkaline Water?

The Reverse Osmosis process does not produce alkaline water, on the contrary, the process produces acidic water due to the produced water’s exposure to air which reduces its neutral pH level of 7 to an acidic pH range of 5 – 5.5. To make RO water alkaline, it is necessary to add calcium and certain other minerals to it. 

What Are the Features of Best Reverse Osmosis Water Filters?

The features of the best reverse osmosis water filters are listed below:

  • Compactness: It is highly favorable that an RO system will be compact in size and design because in most cases, these systems are used for residential or commercial purposes, meaning that they are used in rooms and therefore they are not expected to occupy too much space. 
  • Efficiency in Water Filtration/Purification: The number of pre and post-filter cartridges and the membrane build quality are the most important features that a high-quality RO system should possess because the higher the number is, the better the results will be as long as the cartridges and the membrane are in proper working condition. An RO System’s capability for remineralization and micro-filtration is also an especially determinant factor in establishing its high quality as the processes have a direct impact on the resultant water quality. 
  • Economic Efficiency: It is expected of an RO system to operate with high levels of economic efficiency because as previously stated, most RO systems are used in residential or commercial activities and therefore their end-users have constraints of time, resource, and capital.
  • Long Service Life: Most end-users of RO systems consider them to be long-term investments that will yield economic savings and ease of use for long periods. This is why the best RO systems have long service lives because they are installed once and with proper technical maintenance and repair, they are expected to serve their end-user for long periods. Additional accessories like a TDS Meter, an electric booster pump, and a smart faucet are also considered to be common features of the best RO systems that can prolong their service life. 

How to Choose the Best Reverse Osmosis Water Filter System?

Like many other integrated and essential systems, an RO Water Filtration system comes in different types with different functions and capabilities. Any Reverse Osmosis water filter system buying guide will tell its reader that the first choice to be made when choosing the best RO system is between a Countertop RO System and an Under Counter RO System as they are the two available types in the market today. The first type, commonly referred to as a freestanding RO system, can be located on a countertop or the ground and has a compact design to cover the most minimal space possible without requiring a complicated installation process. They are also temporary and portable, which means that they can be transported to a different place if need be. However, these systems are also considered to be less convenient to use especially in applications expected to produce large quantities of water. The second type operates the same RO system but is installed under a counter, having a sophisticated installation process that generally requires professionals to be involved and producing large quantities of wastewater. Regardless, when these systems are installed, they are extremely easy to use and can produce large quantities of water without any problems.   

Regardless of which type of RO system to be chosen, the purchaser is expected to pay attention to several factors, namely the cost, the size, the water production capacity, system effectiveness, ease of use, the amount of wastewater, and service life. All of these factors show significant variation among different RO system models and therefore they have varying levels of satisfying different end-user expectations, making research and pre-planning highly important when reaching a decision. 

The most common mistakes that consumers make when choosing an RO system are choosing a system and a model, based solely on recommendations or reviews by others and not paying attention to space, material, and technicality-related details regarding RO systems. The best way to handle the research and decision-making processes for the purchase of an RO system is to carry out extensive online research to develop a proper idea about possible options and finalize the decision with a professional or an experienced person in the field of water filtration. All the previously manufacturers, namely Aquaphor, APEC, iSpring, NU Aqua, Waterdrop, Frizzlife, Express Water, Home Master, and RKIN, AquaPure, Brondell, Global Water, Hydrotech, PurePro, Vitev, and Watts, offer extensive product, model, manufacturing, materials, and contact information on their websites and in their stores, so it would be a wise decision to communicate with several different company representatives when considering purchasing an RO system to obtain the most reliable type of information and make the necessary comparisons to reach a sound decision.

What are the Most Quality Reverse Osmosis Water Filter Brands?

The highest quality Reverse Osmosis water filter brands are:

  • Aquaphor: The company is heavily invested in Research and Development projects concerning RO technologies and manufactures highly innovative products.
  • APEC: The company pays special attention to its post-filters to ensure that the taste and texture of the RO water its systems produce is ideal for human consumption, always being associated with tasty water that can be directly drunk or be used in cooking.
  • iSpring: Unlike some of its competitors, iSpring manufactures all the components of the RO system itself and thus offers highly integrated and easily maintainable/repairable products to its customers. 
  • NU Aqua: Nu Aqua is a highly customer-friendly company that focuses on residential RO systems to meet the demand for RO systems in residential areas mostly, keeps an online blog for customer reviews, opinions, suggestions, and stories, while also holding periodic sales campaigns to offer significant discounts and opportunities to its customers.  
  • Waterdrop: Waterdrop invests substantial amounts of money into R&D regarding filters and filtration systems and thus offers some of the most competitive and functional filters and filtration systems enclosed in compact designs for home and office use at reasonable prices. The company also offers important advice, suggestions, and tips over its online blog.  
  • Frizzlife: Frizzlife specializes in Countertop and Tankless RO systems and offers numerous products with different functions, features, and benefits to its customers, while also running a global Distributorship and Drop-shipping campaign to extend its business network. 
  • Express Water: Apart from having all the regular RO systems for residential and office use, Express Water also specializes in Whole-House systems to offer integrated solutions to entire buildings, while running an active Blog and Newsletter over its website.
  • Home Master: As the name suggests, Home Master specializes in residential RO systems with an emphasis on Under-Sink models that come equipped with a tank, offering numerous models in complete sets as well as all the necessary repair and maintenance services.  
  • RKIN: RKIN RO systems are not only highly functional but also compact and intelligent in their design, making them preferable for home and office use. The company also runs a Blog and carries out frequent Giveaway campaigns over its website. 
  • AquaPure: Apart from the generic RO systems, AquaPure also manufactures task-specific RO systems that have been designed to filter and purify greywater, polluted water, brackish water, and saltwater.
  • Brondell: RO systems are only one of the products that Brondell manufactures and the company specializes in highly efficient Under-Counter RO systems that come with full maintenance and repair support.  
  • Global Water: Global Water also deals with various different fields of water treatment business, with its Under-Counter RO systems being highly efficient and having large production capacities. 
  • Hydrotech: Hydrotech is well known for its user-friendly Under-Counter RO systems that offer high-quality water for long periods of time before requiring repair or maintenance that are both very easy to carry out, thanks to Hydrotech’s intelligent products designs. 
  • PurePro: The highlight of PurePro’s company profile is the extensive product line it offers to its customers that consists of highly efficient and easily repairable/maintainable RO systems and spare parts.  
  • Watts: Watts RO systems have sturdy industrial designs and therefore last for long periods of time without requiring any repair or maintenance, while the company has more than 15 different brands that deal with varying fields of water filtration business. 

What Are the Most Quality Reverse Osmosis Products?

The highest quality Reverse Osmosis water filter products are:

  • Aquaphor RO-101S: The model is suitable for all household water purification needs and successfully replaces premium bottled water as the model offers 99.9% filtration/purification efficiency against toxic substances, pesticides, bacteria, viruses, and heavy metals, saving up to 9 tons of water per year, and working at even the lowest water pressure levels in the water supply.  
  • NU Aqua Tankless 600 RO System: The model is a highly rated product that is super-efficient in operation and comes with a unique remineralization filter, a smart faucet for ease of use, and a 120-day guarantee for residential trials.
  • Frizzlife PD-600-TAM3 RO System: The product is a tankless model that is also a highly efficient system that comes with a unique remineralization glitter and a built-in TDS meter. 
  • NU Aqua 7 Stage RO System: The model offers seven stages of filtration along with several other features like UV light filtration and a unique remineralization filter. 
  • Waterdrop G3 RO System: The product is a highly smart model with an integrated TDS meter, a custom faucet, and comes with an NSF/ANSI certification for high production. 
  • Home Master TMHP HydroPerfection RO System: The model houses almost every type of available filter, including the UV filter, making the product ideal for well water applications. 
  • Home Master TMAFC-ERP RO System: The product comes with a high-pressure storage tank, a special remineralization filter, and a passive electric pump, making it ideal for combined use with an Ice Maker. 
  • Frizzlife WA99 Countertop RO System: The model is considered to be the best countertop option because of its extremely easy installation, high efficiency, transportability, and 4-stage filtration system making it ideal for residential or office use. 

What Are the Materials Used in Reverse Osmosis Water Filters?

Apart from the housing, piping, drainage, and physical components that are made of various types of metals such as aluminum, steel, copper, and iron, as well as other materials such as plastic, the main materials used in an RO system can be categorized as the materials used in the carbon filters and the RO membrane. 

  • Materials Used in Carbon Filters: Carbon filters are the most common type of filters used in water filtration, especially for residential purposes, with the material composition being activated carbon placed on charcoal with the determinant factor for carbon’s level of purification being its molecular weight, pH level, surface area, the water’s flow strength and rate, and particle size being filtered. A carbon filter contains numerous forces of attraction within its molecular surface that attract molecules of various kinds, operating similarly to the force of gravity, eliminating contaminants in the water by keeping them within the large carbon surface area. It is essentially the non-polar nature of the carbon that determines such interactions between contaminants and the filter with the electrical charges surrounding the carbon molecules being evenly distributed throughout the surface to cancel out all other charges interacting with the contaminants.    
  • Materials Used in the RO Membrane: As for the RO membrane, it is composed of a three-layered thin-film composite, namely a supportive web made of polyester, a microporous inner layer made of polysulfone, and an ultra-thin barrier layer made of polyamide placed on the top of the membrane unit. The given film composite membranes follow a spiral formation, containing anywhere between one to thirty sheets based on the diameter and the type of the element, being placed inside of a pressure vessel in a series format. The contents of the layers sequentially feed each other, with the concentrate of the first layer feeding the second layer, etc., Interconnectors or couplers are used to interconnect the permeate tubes with the combined total content exiting the pressure vessel on only one side of the vessel and the membranes being positioned around a punctured permeate pipe. Two membranes are placed on three sides with an opening that leads to the permeate pipe and the feedwater flowing across the surface of the membrane, moving from one side to the other. The high pressure in the vessel leads a certain portion of the water to penetrate the membrane and leave through the permeate pipe and constrains the remaining high-concentration water on the other side of the membrane as it flows across the sheet.    

What is the Average Capacity of a Reverse Osmosis Water Filter?

The average capacity of a Reverse Osmosis water filter is about 10 to 75 gallons of water per day. Under 40 to 100 PSI of water pressure, an RO system manufactured by leading companies like Aquaphor, APEC, iSpring, NU Aqua, Waterdrop, Frizzlife, Express Water, Home Master, and RKIN, AquaPure, Brondell, Global Water, Hydrotech, PurePro, Vitev, and Watts, will usually produce water in this range, equating to 50% to 75% of the systems Gallons Per Day (GPD) rating.

Where to Buy a Reverse Osmosis Water Filter?

An RO system can be purchased at various venues or through different channels with the most dominant demand coming from urban areas of the developed world, such as North American metropolis and cities, while smaller cities such as Trinity, Alabama, and Flint, Michigan showing increased demand due to the infrastructural problems observed in their water systems. The different venues and channels through which RO systems can be purchased include:

Hardware stores

Plumbing equipment stores 

Hydroponics stores

Manufacturers’ websites

Online department stores (Amazon, Home Depot, etc.)

Is there a Portable Reverse Osmosis Water Filter System?

Yes, there is a portable Reverse Osmosis water filter system Most countertop RO systems are portable. The advantages of portable Reverse Osmosis water filter systems are their relatively small size and compact design that keeps the entire system within an enclosed housing unit that is easy to hold and carry around. Some of the Best Portable Reverse Portable Water Filtration Systems include AquaTru Countertop RO System, Frizzlife WA99 RO Countertop Water Filter, Zero Installation Purifier Countertop RO System, Crystal Quest Thunder Portable Countertop RO System, Waterdrop WD-G3-W Tankless RO System, and PuroSmart RO System. 

How to Replace a Reverse Osmosis Water Filter?

Due to its compartmentalized design and manufacture, an RO system will allow different components to be replaced when necessary and the pre and post-filters used in the RO system are some of the most important components that need to be replaced periodically. When responding to the question ‘How to Replace a Reverse Osmosis Water Filter?’, there is a list of steps involved in the RO process that need to be taken into consideration, which begins with acquiring the right type of replacement filters as recommended by the manufacturer of the RO system because RO filter replacements are not standardized, meaning that they show variance in size, material, content, and functionality. The replacement TO filters should be kept in their packaging until they are ready to be used to prevent the filter from trapping dirt and air from the surroundings as such particles will reduce the filters’ lifespan. Before the installation of the replacement filters, the hands of the person who will carry out the installation need to be sanitized using water and soap, to prevent the transfer of bacteria from the hands to the unit. To prepare the RO system for maintenance, it is necessary to cut off the water supply, shut off all the valves controlling the system’s storage tank and the refrigerator or any other appliance connected to the system, and turn on the RO bypass valve to allow continuous water flow into the faucet without going through the filter. During this process, it is also recommended that a container be placed under the filter housing to capture any water spilling out of the system during its disassembly stage. In the next step, it is necessary to locate the housing unit that stores the filter to be replaced, which is important because most RO systems have different compartments designated for different filter types with instructions and indicators on such housing units explaining which filter is stored inside, making it easy for the person replacing the filter locate the right filter to be replaced, as replacing the wrong filter will have substantially damaging effects on the system’s operation. After unscrewing the right housing compartment with a wrench and locating the filter to be replaced, the o-rings/gaskets near the compartment screws should be inspected for any wear and tear and should be replaced in case of damage to prevent leakage. The old filter should be removed by sliding it out of the housing and the housing should be washed properly with a brush and pressurized water and the new filter should be inserted and the housing should be prepared for re-installation, meaning that a silicone lubricant should be applied to the o-rings before they are re-inserted in their appropriate spots. In the final step, all the valves shut off, and the water supply line that was cut off previously should be re-activated before the RO system is returned to its operational state.

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