Drinking Water - Washington Tracking Network (WTN)

Why should I be concerned about contaminants in drinking water?

  • If present in drinking water, nitrate can impair our blood's ability to transport oxygen. Nitrate contamination of drinking water can come from the agricultural use of fertilizers and manure, septic tank and waste water effluent, and the disposal of animal wastes.
    • Less than 0.5% of our public water systems have reported nitrate levels above the federal limit of 10 mg/L.
  • If present in drinking water, synthetic organic compounds (SOCs) such as Atrazine and Di [2-ethylhexyl] phthalate (DEPH), and volatile organic compounds (VOCs) such as tetrachloroethene, also called perchloroethylene (PCE), and trichloroethylenes (TCE) can cause a long-term potential health risk.
    • In Washington State these compounds rarely occur in our drinking water and all community water systems that were tested met the standard.
  • Haloacetic acids (HAA5) are disinfection by-products (DBPs) formed when chlorine is used to disinfect water. HAA5 can vary seasonally and are generally tested every quarter on water systems where disinfection is necessary. If present in drinking water, DBPs can cause a long-term potential health risk.
    • About 0.8% of tested systems test above the maximum contaminant level of 60 µg/L.

View the Data

Drinking Water Data

Learn More

To learn more about drinking water and your community water system, visit our Drinking Water webpage.

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For information or questions related to the Washington Tracking Network, email DOH.WTN@doh.wa.gov.

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National Environmental Public Health Tracking Program