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Portland Water Bureau

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Water Bureau Flushing Water Mains in North Portland Neighborhoods

By Lindsay Wochnick

To clean and maintain the drinking water system, the Water Bureau uses Unidirectional Flushing (UDF) to scour and clean the insides of the water delivery pipes. 

The Portland Water Bureau is currently conducting UDF flushing of the water mains in the St Johns and Cathedral neighborhoods in north Portland.

Flushing is occurring between N. Iris Street on the north, to Bradford Street on the south, from St Louis Avenue on the east, to Roberts Street on the west. CLICK HERE to view a map of the flushing area.

Flushing in St Johns is expected to be complete in September 2016.

Using Water Wisely this Summer
Flushing water from hydrants is an important and necessary practice to maintain water quality in the distribution system. This practice is used to flush discolored water from the pipes, keep water fresh in low use areas and dead-ends, and to clean inside pipes. This process is regularly monitored by Water Bureau staff to make sure the water is used wisely while maintaining water quality.

What you can Expect to See
Unidirectional flushing will have minimal impacts to customers. If you see hydrant flushing crews working in the area, please drive carefully and treat them like any other road construction crew.

During flushing, residents in the immediate vicinity of flushing may notice temporarily discolored water and lower than normal water pressure. The discoloration does not pose a health risk. However, you may wish to avoid using tap water or running the washing machine or dishwasher until your water runs clear. After flushing, if you still experience discolored water, turn on each cold water faucet in your house and allow them to run for several minutes or until the water is clear.

Flushing usually occurs Monday through Friday, between 9 a.m. and 3 p.m.

How Does UDF Work?
UDF works by forcing water in the pipes to flow at much higher speeds than normal. Flushing crews first open and close valves to isolate sections of pipe, and then the water and any sediments in the pipes are flushed out through an open fire hydrant. Residents may observe water gushing from an open hydrant.

Improving and Maintaining High-Quality Drinking Water
Drinking water systems, especially unfiltered systems like Portland, need to routinely clean the network of pipes to improve water quality. Over time, very fine sediment and organic matter from the Bull Run settle out of the water and accumulate in the bottom of the pipes. While the sediments are generally harmless, they can make the disinfectant in the water less effective. Additionally, sudden changes in the flow of water can disturb these sediments resulting in discolored water.

Call the Portland Water Bureau Water Line from 8:30 am to 4:30 pm at 503‐823‐7525 with any questions or to report ongoing water quality problems. For more information, updates, and maps, visit


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