Frequent Questions

Our water has tested at 15 mg Nitrate vs EPS standard of 10 mg. We are looking at a reverse osmosis system. Would a system on the kitchen sink used for drinking water be adequate, or is a whole house system required?

Nitrates in water used for showering or bathing is not a health concern. Nitrates in drinking water above the federal standard (10mg/L) can be very harmful if ingested, so a treatment device on taps that dispense water primarily for drinking or cooking is recommended.  

EPA neither endorses nor recommends specific home water treatment units. Consumers who choose to purchase a home water treatment unit should carefully read its product information to understand what they are buying, whether it is a better taste or a certain method of treatment. Be certain to follow the manufacturer's instructions for operation and maintenance, especially changing the filter on a regular basis. For more information download the booklet: Filtration Facts at  

For help in picking a unit, contact one of the following independent non-profit organizations:

    * NSF International  (800-673-8010,
    * the Underwriters Laboratories Inc. (888-852-3638,
    * and the Water Quality Association (630-505-0160,

Both NSF International and Underwriters Laboratories Inc. test and certify home water treatment units. The Water Quality Association classifies units according to the contaminants they remove as well as listing units that have earned their “Gold Seal” approval. Water treatment units certified by these organizations will indicate certification on their packaging or labels.

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