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Reverse Osmosis Purification Process

Why RO

If you want to

  • Drink healthy water
  • Feel energized 
  • Prevent disease
  • Have on-demand access to pure, alkaline water
  • Solve hard water problems or bad odors
  • Improve taste of your drinking water
  • Be environmentally responsible
  • Save money and hassle - RO is the most cost effective solution on the market today

you should consider installing an Reverse Osmosis system in your home.

How Does Reverse Osmosis Work:

Backed by over 40 years of industry experience solving the toughest and the most common water issues, we bring our industry-leading technology and experience right into your home or commercial space.

Reverse Osmosis (RO) is the most effective and economical way to provide your family or employees with a high-quality drinking water straight to your faucet. 

It's a process by which water molecules are forced by your household water pressure through a semipermeable membrane. Contaminants are rejected and rinsed to the drain while your high quality, filtered water is stored in the holding tank.

In addition to removing excess or harmful minerals, reverse osmosis removes odor, color, chemicals, contaminants and other organic compounds, which contribute to bad taste or health concerns. 

Today, RO water filtration process is the only way to remove all harmful impurities from your water and do it in a cost effective, efficient way.

How Does FreePurity Reverse Osmosis System Filter The Water:


The RO systems are modular which means you can add many filter stages (steps) to the system so don't be surprised if you see 2,3,4,5 or even 7 and 10 stage RO systems. Keep in mind that every stage requires additional maintenance costs to replace filters so it's advisable to only use as many filter stages as necessary to achieve a desired result. Each state and city in the United States has a yearly water report you can check to learn which contaminants you should remove from your drinking water.


    Certified Contaminants Reduction

      - Arsenic 99.6%     - Copper
      - Barium
    99.8%     - Fluoride 97.7%
      - Cadmium 99.8%     - Lead 99.3%
      - Chromium (Hexavalent) 99.1%     - Radium 226/228 80.0%
      - Chromium (Trivalent) 99.7%     - Selenium 98.1%

    Full List Of Contaminants Reduction:

    Sodium Yes Chromium-6 Yes
    Calcium Yes Chromium-3 Yes
    Magnesium Yes Sodium Yes
    Potassium Yes Lead Yes
    Iron 2 Yes Chloride Yes
    Manganese 2 Yes Bicarbonate Yes
    Aluminum Yes Nitrate3 Yes
    Copper Yes Fluoride Yes
    Nickel Yes Phosphate Yes
    Zinc Yes Chromate Yes
    Strontium Yes Cyanide Yes
    Cadmium Yes Sulfate Yes
    Silver Yes Arsenic + 3 Yes
    Mercury Yes Arsenic + 5 Yes
    Barium Yes Selenium Yes
    Radioactivity Yes Asbestos Yes
    Bacteria Yes Sediment Yes
    Protozoa Yes Turbidity Yes
    Ameobic Yes Giardia Yes
    Cysts Yes    
    Organic Contaminants Organic molecules with a molecular weight < 300 Yes Organic molecules with a molecular weight < 3005 Yes

    Volatile Organic Chemical (VOC) Reduction

    Carbon Tetrachloride
    Dibromochloroproane (DBCP)
    Ethylene Dibromide (EDB)
    Haloacetonitriles (HAN)
    Haloketones (HK)
    Heptachlor (H-34,Heptox)
    Heptachlor Epoxide
    2,4,5-TP (Silvex)
    Tribromoacetic acid

    Let's Break Down The 4-Stage Reverse Osmosis Purification System

    Please note depending on the application, RO systems come in multiple stages as you can add additional filtration stages (mostly additional carbon filters) as necessary or remineralization cartridges. FreePurity can custom build a system that is multistage and appropriate for your particular needs based on the water quality in the area. 

    Stage 1 - Sediment filter

    • Sediment filter reduces larger particles such as dirt, rock, sand grains, rust and other visible contaminants.
    • Replacement recommendation every  4~6 months - depending on your water quality.

      Stage 2 (and 3 if 5 stage) - Activated Carbon Filter 

      • Carbon filter reduce chemicals, such as chlorine, and other taste and odor causing compounds.
      • Replace 1yr  depends on your water quality.
      • For Systems with more than 4 stages, additional carbon filters are added.

      Stage 3 (or 4 if 5 stage) - Reverse Osmosis Membrane

      • This is the power horse of the entire system, all other filters prep water for this stage. Reverse Osmosis membrane reduces 93%-99.99% of dissolved minerals, salt and other contaminates from your water supply.  This is where the purification takes place.
      • Replacement recommendation every 2-5 years depending on your water quality and choice of a membrane. Membranes can filter from 36-100 GPD for residential systems. Large commercial and industrial membranes have no filter capacity limits. 

      Stage 4 (or final stage if 5 stage) - Post Carbon Filter

      • Post Carbon Filter is polishing process that removes tastes and odors out of water
      • Replacement recommendation every 1-2 years depending on your water quality. 

      5-Stage vs 4-Stage systems have additional carbon filter prior to passing water through the membrane. Customers may add UV filters and alkaline cartridges to increase alkalinity which will make these Stage 6 or 7...customization is available on all systems sold by FreePurity.

      If a system has 5 stages, there's an additional Carbon Filter added to the process. This 

      Benefits of RO water include:

      RO water is safer, the most cost effective, filters on demand, healthier, has no smell and tastes refreshing. Based on our research, no other process is as effective. 

      • Safe drinking water: Consumers want safe, healthy, good-tasting water. RO purified water meets the requirements of the Safe Drinking Water Act and EPA standards for drinking water.
      • Great taste: RO removes excess minerals, odor, color, and other organic compounds that contribute to bad taste.
      • Improved Health: RO membranes provide a barrier to bacteria and virus resulting in healthier water for drinking and cooking.

      Basic Components of a Reverse Osmosis System:

      Generally, residential RO Systems are installed and stored under the kitchen sink. Regarding the common components of a - stage RO system, note that:

      • Most RO systems look similar and have the same basic components.
      • Although most RO systems look and work basically the same way --they differ in the QUALITY of their components.
      1. Cold Water Line Valve: Valve that fits onto the cold water supply line. The valve has a tube that attaches to the inlet side of the RO pre-filter. This is the water source for the RO system.
      2. Pre-Filter(s): Water from the cold water supply line enters the Reverse Osmosis Pre-Filter first. There may be more than one pre-filter used in a Reverse Osmosis system, the most common being sediment and carbon filters. These pre-filters are used to PROTECT the RO membranes by removing sand silt, dirt, and other sediment that could clog the system. Additionally, carbon filters may be used to remove chlorine, which can damage the RO membranes.
      3. Reverse Osmosis Membrane: The Reverse Osmosis Membrane is the heart of the system. The semipermeable RO membrane is designed to remove a wide variety of both aesthetic and health-related contaminants. After passing through the membrane, the water goes into a pressurized storage tank where treated water is stored.
      4. Storage Tank: The standard RO storage tank holds from 2 - 4 gallons of water. A bladder inside the tank keeps water pressurized in the tank when it is full. The typical under counter Reverse Osmosis tank is 12 inches in diameter and 15 inches tall.
      5. Post filter(s): After the water leaves the RO storage tank, but before going to the RO faucet, the treated water goes through a final “post filter”. The post filter is usually a carbon filter. Any remaining tastes or odors are removed from the product water by post filtration “polishing” filter.
      6. Automatic Shut Off Valve (SOV): To conserve water, the RO system has an automatic shut off valve. When the storage tank is full, the automatic shut-off valve closes to stop any more water from entering the membrane and blocks flow to the drain. Once water is drawn from the RO faucet, the pressure in the tank drops; the shut-off valve then opens to send the drinking water through the membrane while the contaminated wastewater is diverted down the drain.
      7. Check Valve: A check valve is located in the outlet end of the RO membrane housing. The check valve prevents the backward flow of treated water from the RO storage tank. A backward flow could rupture the RO membrane.
      8. Flow Restrictor: Water flowing through the RO membrane is regulated by a flow restrictor. There are many different styles of flow controls, but their common purpose is to maintain the flow rate required to obtain the highest quality drinking water (based on the gallon capacity of the membrane). The flow restrictor also helps maintain pressure on the inlet side of the membrane. Without the additional pressure from the flow control, very little drinking water would be produced because all the incoming water would take the path of least resistance and simply flow down the drain line. The flow control is most often located in the RO drain line tubing.
      9. Faucet: The RO unit uses its own faucet, which is usually installed on the kitchen sink. Some areas have plumbing regulations requiring an air gap faucet, but non-air gap models are more common
      10. Drain line: This line runs from the outlet end of the Reverse Osmosis membrane housing to the drain. The drain line is used to dispose of the wastewater containing the impurities and contaminants that have been filtered out by the reverse osmosis membrane.
      11. Feed line: The line that runs from your cold water pipe to the 1st RO stage. 
      12. Faucet line: The line that runs from the final post filter (or polishing filter) to the faucet.
      13. TDS meter: These meters test water quality anytime, anywhere so you change filters only when necessary saving time and money.