national sanitation foundation

The NSF Mark can be found on millions of consumer, commercial, and industrial products today. Products evaluated and certified by NSF International include bottled water, food equipment, home water treatment products, home appliances, plumbing and faucets, and even pool and spa components.

The next time you are shopping for a food or water-related product that may potentially affect the health of you or your family, look to see if the NSF Mark is on the product. This Mark is your assurance that the product has been tested by one of the most respected independent certification companies in existence today, NSF International.

The NSF Water Treatment Device Certification Program requires extensive product testing and unannounced audits of production facilities. The goal of this program is to provide assurance to consumers that the water treatment devices they are purchasing meet the design, material, and performance requirements of national standards.

Selecting and Using Water Treatment Devices
Drinking Water Treatment Technologies
Styles of Water Treatment
The Importance of Certification
Drinking Water Treatment and Homeland Security
Additional Information
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Selecting and Using Water Treatment Devices

Many consumers have difficulty determining whether they actually need a water treatment system or they are not sure what type of system would be best for them. The choice regarding whether or not to install and use a water treatment system is up to you. If you have identified a specific contaminant whose presence in your water is causing you concern, you can use the drinking water treatment units online product database to try to locate products that have been certified to reduce that specific contaminant.

Consumers are encouraged to educate themselves about the quality of their current drinking water supply. By attempting to identify the contaminants that are present in your water supply, you can then ensure that you are selecting a water treatment system that will be capable of treating those specific contaminants.

It is important to keep in mind that all home water treatment devices need regular maintenance to operate effectively. Please read the operating manual that comes with your water treatment system to ensure you are operating your system in accordance with the manufacturer's directions. Filter cartridges should be changed on a regular basis as recommended by the manufacturer.

Drinking Water Treatment Technologies
The products on the market today utilize many different technologies. NSF currently evaluates residential water treatment products that utilize one of the technologies listed below. The applicable NSF/ANSI standard that applies to each technology is shown in parentheses.

Technology    Description of Product    Technology

Filtration        (NSF/ANSI 42 & 53)        This is the physical process that occurs when liquids, gases, dissolved or suspended matter adhere to the surface of, or in the pores of, an adsorbent medium. Carbon filters use this technology to filter water.

Softeners       (NSF/ANSI 44)                 Water softening devices covered by Standard 44 use a cation exchange resin, regenerated with sodium chloride or potassium chloride, to reduce the amount of hardness (calcium, magnesium) in the water. The hardness ions in the water are replaced with sodium or potassium ions.

UV                  (NSF/ANSI 55)                This treatment style uses ultraviolet light to disinfect water (Class A systems) or to reduce the amount of heterotrophic bacteria present in the water (Class B systems).

Reverse Osmosis   (NSF/ANSI 58)         A process that reverses, by the application of pressure, the flow of water in a natural process of osmosis so that water passes from a more concentrated solution to a more dilute solution through a semi-permeable membrane. Most reverse osmosis systems incorporate pre- and post-filters along with the membrane itself.

Distillers          (NSF/ANSI 62)                These systems heat water to the boiling point and then collect the water vapor as it condenses, leaving many of the contaminants behind, particularly the heavy metals. Some contaminants that convert readily into gases, such as volatile organic chemicals, may be carried over with the water vapor.

Styles of Water Treatment Devices
There are several styles of water treatment devices available on the market today. The most common styles are listed below, along with a brief description of each.

Point-of-Entry (POE) System
These systems typically treat most of the water entering a residence. Point-of-entry systems, or whole-house systems, are usually installed after the water meter. (Water meters are usually located in the basement of a house. In warm weather climates, the water meter may be in the garage or outside of the house.) A water softener is an example of a POE system.

Point-of-Use (POU) System
These systems typically treat water in batches and deliver water to a single tap, such as a kitchen sink faucet or an auxiliary faucet mounted next to the kitchen sink. The following information contains a brief explanation of different POU systems and points to consider when determining which style of a system will best suit your needs. The list is ordered from easiest installation/operation to more difficult or complex installation/operation and should not be construed as any type of recommendation