News Flash


Posted on: November 29, 2023

City of Napa Announces Launch of Annual Hydrant Flushing Program

Hydrant Flushing

The City of Napa Water Division will begin the annual Hydrant Flushing Program during the first week of December. This year’s program is expected to continue through February 2024 and will include various areas as shown in the attached map. 

Hydrant flushing is an important maintenance activity to clean and flush the City water mains. Fire hydrants are opened to move a large volume of water at a higher-than-normal velocity through the mains. This procedure mobilizes particles and minerals that have settled over time and flushes them out of the system. This activity assists the City in maintaining the highest quality of water in the public water system and to ensure hydrants are operating properly for Fire Department use. 

To sustain our high water quality, we must perform flushing activities each year. The amount of water used this year, about 8 million gallons, will be less than all customers’ combined use for irrigation on a single summer day. Flushing is a necessary use of water to help maintain water quality. 

This program may cause periods of discolored water and reduced water pressure in localized areas where flushing is being conducted. The discoloration of water is due to mobilization of particles that have settled in the water main by the high velocity water before being discharged through the fire hydrants. The water will remain safe to use and generally clears within a few hours after flushing has been completed. Residents should monitor their water prior to starting laundry, especially when washing white clothes. 

Although customers will continue to have water service during this program, flushing operations may activate low-pressure alarms on automatic fire sprinkler systems due to temporary reductions in water pressure. 

Commercial customers, especially businesses that serve the public, should be aware of the water quality while flushing is taking place in their area. 

The hydrant flushing staff will be using dechlorination tablets to remove chlorine in the water before the water goes into the storm drain system and eventually into the Napa River. Due to the high velocity of water flowing from the hydrants, the dechlorination tablets may cause some bubbling of the water, giving it a soapy appearance. The tablets are environmentally safe and are being used to protect the river. 

Due to the nature of the flushing program, it is difficult to determine the exact day we will flush in each area. For that reason, the Water Division will update the City’s website regularly to provide a map of the region being flushed each day and a map of the region that will be flushed next, to help keep the public up to date on our progress. The flushing program maps and updates can be found at:

The City thanks Napa residents and businesses for their patience and apologizes for any inconvenience our program may cause. Please contact the City of Napa Water Division at (707) 257-9521 with any questions or concerns.

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