Water Quality

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Public Drinking Water

  Quick Summary - check check checkClimate Change Indicator
Significant improvement in drinking water quality in 2019, but chloride was again the most common contaminant detected in public water systems.

This indicator shows the percentage of the population served by Community Water (C) systems and Non-Transient Non-Community Water (NTNC) systems that demonstrated full compliance with applicable standards, after weighting the reports to account for the number of people served by each system. Though long-term problems occur, they are rare in large systems. Data for 2019 show a substantial decrease in the number of violations from 2017 and 2018 levels. Significant improvements from two large water systems in the state resulted in a decrease in violations of disinfection byproducts and other chemicals. By far, the most common problem during 2019 in water systems was excessive levels of chloride,** which is typical of most years. The Connecticut Department of Public Health (DPH) oversees the monitoring for lead by public water supplies, and also requires public water to be tested for corrosive properties (including pH) that could lead to lead contamination. Lead contamination is uncommon in Connecticut. A 2019 report by the Auditors of Public Accounts for calendar year 2017 recommended that the DPH strengthen oversight and enforcement.

CT Water Plan: In 2019, the legislature ratified the State Water Plan. It establishes a framework for balancing human and environmental needs for water. It addresses the quality and quantity of water for drinking, ecology, recreation, business, industry, agriculture, energy, and wastewater assimilation, in the context of a changing climate.

About 80 percent of people in Connecticut are supplied by the public water systems included in the chart above. The remainder of the population relies on private wells, which are not monitored by any government agency and are not counted in this indicator. An unknown but significant number of private wells are contaminated by pollution or naturally-occurring toxins such as arsenic and uranium. Residents who drink from private wells are not required to test their water routinely, so the number of people who drink contaminated water from private wells cannot be measured.

In 2019, the Department of Public Health and DEEP developed a comprehensive strategy to address per- and polyfluoroalkyl substances (PFAS) in Connecticut’s environment. Although Connecticut’s large Public Water Systems conducted multiple rounds of testing from 2013 to 2015 and did not detect PFAS in the water from their sources of supply, it remains a concern.  These sources of supply provide drinking water for over 2.4 million daily customers in CT. Moreover, leaking heating fuel systems can impact drinking water supplies as detailed in the Council’s 2019 report Fuel for Thought.

Technical Notes: *The vertical axis in the chart above has been shortened, beginning at 97 percent rather than the customary zero. This allows the reader to see year-to-year differences, which would be nearly imperceptible if the chart began at zero. **The standard for chloride is set by state regulation. It is assumed that the goal is for everyone to have safe drinking water.