How Reverse Osmosis Works 

A residential reverse osmosis unit relies on the natural water pressure forcing the water through a semi-permeable membrane. This membrane allows the water to filter through, while rejecting any contaminants. The water then passes through a holding tank where it remains to be used. Reverse Osmosis units require two pre-filters prior to the water passing through the membrane. The first is a sediment filter which traps any fine suspended materials which would clog the membrane, and the second is a carbon filter, which reduces chlorine that would otherwise damage the membrane. Once the water passes through the membrane, it goes through another carbon filter before going to the holding tank. Rejected water is periodically flushed out to avoid scale buildup. The standard efficiency of a reverse osmosis unit is 1 gallon of treated water for every 2 to 4 gallons of rejected water.

* Since the RO unit so thoroughly blocks the drinking water, it is advised to discuss the lack of minerals in the drinking water with a healthcare professional.

A reverse osmosis (RO) unit can be used to treat a number of contaminants that cause unpleasant taste, color, and odor problems. It is often used in conjunction with other forms of water treatment or on household municipal supplied tap water. The U.S. Environmental Protection Agency (EPA) has set specific guidelines for maximum contaminant levels for about ninety substances, however many people feel more comfortable consuming a higher quality of water.
For residential applications, the RO unit is usually installed at the point of use, i.e. under the kitchen sink, to provide treated drinking and cooking water.

Designer RO Faucets

Drinking Water System

3 Stage Ultra Filtration – reduces lead, VOC (pesticides, herbicides, chemicals), THM, chlorine, taste, odor & sediment as small as 0.2 microns.

• Ideal for city water
• Low cost
• Point-of-use treatment option

Health issues may arise from using and consuming water containing certain substances. The following are the most commonly detected contaminants in well water that are associated with health concerns:

• Arsenic
• Bacteria
• Fluoride
• Manganese
• Nitrate
• Radon
• Sodium/Chloride
• Uranium 

Refer to the Connecticut Department of Public Health’s Action Level List for Drinking Water.  The contaminants listed may present a health risk to those who use contaminated water for drinking, bathing, washing, or cooking.

https://portal.ct.gov/DPH/Environmental-Health/Environmental-and-Occupational-Health-Assessment/Action-List-for-Drinking-Water

For information on the health concerns related to regulated contaminants, refer to the U.S. EPA National Primary Drinking Water Regulations (NPDWR):

Download PDF

https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations

A reverse osmosis system or other types of whole house filters can effectively remove health-hazardous contaminants such as:

• Lead

• Mercury

• Nitrate

• PCB’s

• PFAS/PFOS

• Radium

• Sodium

• Trichloroethylene

• Trihalomethanes

• Uranium

• Volatile Organic Compounds

An ultra-violet light unit will disinfect the water by destroying:

• Cryptosporidium
• Giardia
• Viruses

Other contaminants, such as manganese and radon, may also require remediation.

For more information, please see the Connecticut Department of Public Health fact sheets for these contaminants:

Arsenic(V)
https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/private_wells/Publications/ArsenicPrivateWellWater21.pdf

Chloride
https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/private_wells/Sodium–Chloride-FS-sept-2018-update.pdf

Fluoride
https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/pdf/08FluorideinPrivateDrinkingWaterWellspdf.pdf

Lead
https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/private_wells/Publications/05241712LeadinPrivateWellWaterpdf.pdf

Manganese
https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/drinking_water/pdf/Manganese_Fact_Sheet.pdf

Nitrate
https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/pdf/16NitrogenContaminationinPDWWpdf.pdf

PFAS/PFOS
https://portal.ct.gov/DPH/Environmental-Health/Private-Well-Water-Program/PFAS-in-Private-Wells

Radium
https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/eoha/pdf/radiuminwellwaterpdf.pdf

Radon
https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/radon/2021/Radon-in-Your-Well–Water-2021.pdf

Sodium
https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/private_wells/Sodium–Chloride-FS-sept-2018-update.pdf

Uranium
https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/private_wells/2018-Downloads/050818-uranium_in_well_water_September_2016.pdf

Bacteria
https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/pdf/04BacteriainPrivateDrinkingWaterWells0409pdf.pdf