Flushing Dead-End Water Pipes

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Routine maintenance improves water quality

A water operator opens a hydrant to flush a drinking water main.
Water Systems Lead Operator Danny Leonardo
opens the hydrant used to flush a drinking water
main at the end of Trescott Court.

Crews are flushing drinking water lines, as part of the District’s water quality maintenance. This is especially important on courts where water lines end.

Over the years, scale and natural sediments build up in water pipelines, which can reduce chloramine (chlorine and ammonia) disinfectant residuals. Flushing out the pipes is one of the best ways to immediately improve water quality.

The flushing process involves scouring the walls of the water pipes with pressurized water traveling at an average rate of 750 gallons per minute. Then this water is put into the closest wastewater pipes and returned to the Regional Wastewater Treatment Facility where it is recycled into irrigation water.

     A water operator holds up a vial of water to check turbidity in sunlight.
    Water Systems Operator Matt McGrath checks the turbidity of the water after flushing is complete.

Previously, field crews would flush water lines and then would have to remove chlorine from the flushed water, by passing it through a de-chlorination diffuser, so they could put the water in the storm drain system. However, instead of disposing of the water in the San Francisco Bay (that’s where water in our storm drains ends up), we now pipe it back to the treatment plant and reuse it locally as irrigation water.

There about 575 dead-ends in the District’s 320.8 miles of water pipes. Flushing can take 15 minutes to an hour depending how much sedimentation is in each water main. Customers in the immediate area may notice some cloudiness in the water during the process. In this case, run the tap until the water is clear.

What's Happening Now

Starting Nov. 5, 2019, residents in the Dublin neighborhood near Persimmon Drive and Summer Glen Drive will see DSRSD field crews flushing drinking water lines:

 Map of streets in the neighborhood off of Persimmon Drive and Summer Glen Drive.

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