Reverse Osmosis System Buying Guide
What is the Reverse Osmosis (RO) Process?
Water pressure from your municipal water supply or well water supply forces the water molecules through a very fine membrane leaving the contaminants behind. The pores in a reverse osmosis membrane are slightly larger than the water molecule itself and separates the water into two streams. The purified water is collected on the "clean" or “permeate” stream of the membrane, and water containing the concentrated contaminants is flushed down the drain from the "brine" or "concentrate" stream.
Stages of Filtration
The modern RO system is a unit consisting of a sediment pre-filter to remove particulates, turbidity, sand and rust; an activated carbon pre-filter to remove the chlorine, pesticides, herbicides, disinfectants, and VOCs which might otherwise damage the reverse osmosis membrane; the reverse-osmosis membrane which removes virtually everything such as heavy metals, lead, salt, chromium and dissolved solids; a storage tank, and an activated-carbon post filter. The carbon post filter or polishing filter is necessitated by the demineralized, slightly acidic RO water attacking the rubber inside the storage tank, dissolving some of the rubber. This can be avoided by remineralizing the water prior to storage.
- Sediment Stage: removes rough particles, sand and rust.
- Carbon Stage: removes chlorine and chemicals which would otherwise damage the TFC reverse osmosis membrane. Multiple carbon stages my be necessary at this point depending on the carbon quality and contact time.
- Reverse Osmosis Stage: removes dissolved solids and virtually everything larger than the water molecule itself. This is where the bulk of the purification is accomplished.
- Remineralization Stage: water purified by reverse osmosis is highly pure and slightly acidic. The Home Master Artesian Full Contact® remineralizes with calcium and magnesium to balance the pH, improve the taste and introduce healthy minerals. Learn more about Alkaline Water.
- Storage Tank
- Optional or application specific water treatment stage(s): UV filter to destroy microorganisms, nitrate/arsenic/fluoride/deionization selective filters to remove whatever small amount remains of these contaminants.
- Final Carbon stage: also known as a "polishing" filter this carbon filter removes any tastes or odors the acidic RO water has "picked up" from the storage tank. In other words the acidic water produced from systems without the Artesian Full Contact technology will dissolve some of the rubber in the storage tank which the final carbon filter then removes.
Reverse Osmosis Purity
Reverse Osmosis removes salt and most other dissolved inorganic material present in the water, and for that reason, RO lends itself to use in places where the drinking water is brackish (salty), contains nitrates, radionucliatides, heavy metals or other dissolved minerals which are difficult to remove by other methods.
Using a quality carbon filter to remove any organic materials and chemicals that get through the sediment pre-filter, in conjunction with RO produces water with a purity that approaches distilled water. Microscopic parasites (including viruses) are usually removed by RO units, but any defect or micro-tear in the membrane will allow these organisms to pass into the ‘clean” water. This is why RO systems are not rated to remove microorganisms except when an Ultraviolet Light filter is incorporated into the system, such as in the case of the Home Master ULTRA and Home Master HydroPerfection.
Though slower than a water filter, RO systems can typically purify much more water per day than water distillers. While they do not use electricity,like water distillers, RO systems do waste water. Four or more gallons of concentrated waste water are flushed down the drain for every gallon of filtered permeate water produced. Zero waste RO units are available, however problematic, as they can re-inject the concentrated waste water back into the water feeding the RO thus forcing the RO to work harder and shortening its service life. Other types of Zero Waste RO units will inject the wastewater into the hot water line where it is dispensed out of the kitchen faucet on your hands or dishes.
A better option for reducing reverse osmosis system water waste is to fit it with a Permeate Pump, which will reduce water waste by up to 80% and does not use electricity like other Zero Waste systems.
Types of Reverse Osmosis Membranes
Two common types of household RO membranes are the Thin Film Composite (TFC or TFM) membrane and the Cellulose Triacetate (CTA) membrane. The main differences between the two types are filtration ability and chlorine tolerance. The CTA membrane is chlorine tolerant, but is more susceptible to fouling from bacteria, and it only rejects 93% of standard contaminants. The TFC/TFM membranes reject 98% of standard contaminants on average, are less susceptible to organic fouling, but it can only treat chlorine free water. Carbon pre-treatment filters must be used with a TFC/TFM membrane when purifying chlorinated municipal water supplies. Brackish water, saline water, and brine water membranes are available for marine, industrial, and municipal desalinization projects.
Before water filter reviews, consult our buying guide to home water filtration systems. Topics on process, stages, purity, efficiency, more. Know before buying.
- Purification: the NSF certified components and Dow Filmtec reverse osmosis membrane work together to remove dissolved solids like heavy metals, nitrates, lead and fluoride; sediment, turbidity, and rust; and chemical contaminants like chlorine, chloramines, pesticides, herbicides and gasoline additives. Additional purification is available with the iron and UV filters , and the permeate pump upgrade. For more information please see the specific product page and the FAQs page.
- Leak elimination: The leading competitors canister type RO system uses the same filter housing year after year, subjecting it to constant high water pressure, water erosion, and wear from maintenance. Only the filter element is replaced. After about 5 years the walls and seals of the competitors canister filter housing begin to weaken and decay, eventually failing, potentially causing a substantial leak.
- User-friendliness: The first thing you will notice about the Home Master Reverse Osmosis system is that the filters are incorporated into the filter housing, so that when it comes time for the annual filter change, the filter, and the entire filter housing, are disposed of. This is to prevent flooding in your home and make your annual service easier. Just unplug and go - no tools required!
- Efficiency: Home Master RO system uses high grade filters designed to yield 3900 gallons of purified water, with both carbon stages made from coconut shell activated carbon with filtration down to 5 microns. Compression disks in the Home Master's advanced inline filters prevents channeling and dumping and permits an outstanding 10 full inches of carbon contact for greater purification. The competition typically uses lower grade filters made from coal carbon rated to purify just 1500 gallons of water because of the carbon grade and the insufficient carbon contact time made with a thin wall carbon block. The competition also uses recommends multiple Filter Changes per year in order to compensate for their poor quality filters.
- Reduced waste: In designing the Home Master RO a sophisticated combination of flow restriction components were integrated into the system architecture to regulate pressure to and from the 50 gallon per day membrane chamber for optimized water purification and minimized wastewater production. For further system efficiency improvement please consider a Permeate Pump which will reduce wastewater, increase water production, and allow your storage tank to fill fuller.
Reverse Osmosis System Upgrades
- Permeate Pump reduces water waste by up to 80%, increases water production by up to 50%, allows the storage tank to fill fuller, and produces slightly cleaner water by preventing "TDS creep." It is a non-electric pump that harnesses the movement of the waste water for power.
- Anti-Microbial Tubing prevents microorganism growth formation on the inside of the tubing. This upgrade replaces the standard system tubing with antimicrobial tubing.
- Refrigerator Connection Kit allows you to easily connect your Home Master to your refrigerator‚ water dispenser and ice maker. You may also use this kit to connect to some coffee makers, humidifiers, or other water using appliances (not dishwashers or laundry machines).
- Upgraded RO Faucets have more elegant finishes and styles, and deliver greater water flow rate. All Home Masters feature a built in Fast Flow! RO kit which builds up the entire back end of the system with larger fittings and tubing so the water flows faster than competitor's units.