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Drinking Water Quality Notice: Failure to Monitor Turbidity at Washington Aqueduct

August 31, 2020

Important Information About Your Drinking Water

The Washington Aqueduct, which treats and supplies drinking water to DC Water, has notified us of a lapse in turbidity monitoring at one of their 48 filters.

The aqueduct is required to monitor your drinking water for specific contaminants on a regular basis. Results of regular monitoring are an indicator of whether or not your drinking water meets health standards. 

The incident began June 24, 2020 and was discovered and corrected on June 25, 2020, at which time the system returned to full regulatory compliance. Although the overall turbidity of treated water from all filters remained within allowable limits, any lapse in proper monitoring at an individual filter increases the risk to consumers. 

This is not an emergency.  If it had been, you would have been notified immediately, so there is no need for consumers to use alternative water supplies or take other actions.

Please share this information with all the other people who drink this water, especially those who may not have received this notice directly (for example, people in apartments, nursing homes, schools, and businesses). You can do this by posting this notice in a public place or distributing copies by hand or mail.

Why are you telling me this?
DC Water is sharing this operational information with their customers to acknowledge a monitoring problem at the plant.  The treatment plant measures turbidity at individual filters and the combined flow. For a short time, one filter did not have monitoring which was an operational error. 

What do I need to do?
Nothing, the drinking water is safe to consume.  

What is turbidity?
Turbidity is a measure of the cloudiness of water. It is used to indicate water quality and filtration effectiveness.  Water utilities are required to monitor turbidity at different points in the treatment process.  In this case, turbidity was not monitored for 17 hours on June 24-25 at one of Washington Aqueduct’s 48 filters.  During those 17 hours, the overall turbidity of treated water from all filters remained within allowable limits.  The turbidity of the impacted filter was within allowable limits before and after the incident.  

Do I get a credit on my bill for this?
No, DC Water delivered water that met all EPA’s requirements for safe drinking water. If there was a reasonable likelihood that the water quality was adversely affected, then we would have notified you immediately to take action.

What are the regulatory requirements for this type of incident?
This incident was designated as a Tier 3 Public Notification under the EPA’s Public Notification Rule, which is part of the Safe Drinking Water Act.  A Tier 3 designation means that the violation does not have a direct impact on human health.  The regulation states that the water supplier has up to a year to provide a notice of this situation to its customers.  In addition to this notice on our website, DC Water will include a notice in the 2021 Annual Water Quality Report which will be released next year.

Who can I contact for more information?
Please contact our Drinking Water Department at (202)612-3440 or by email at