To help maintain the health of Hillsboro’s water system, the City of Hillsboro Water Department officially implemented a new, year-round unidirectional flushing (UDF) program this week.
UDF involves flushing water mains – or the underground pipes that deliver drinking water to homes and businesses – through fire hydrants. UDF is a standard industry maintenance practice that helps maintain water quality and improve the carrying capacity of water mains. Flushing will also prepare Hillsboro’s water system for the integration of the Willamette Water Supply System in 2026.
“Over time, small amounts of sediment from mineral deposits and organic matter can settle out of the water and accumulate in the bottom of water mains,” said Jessica Dorsey, Hillsboro Water Resources Division Manager.
“Sediment can build up in water mains and eventually affect the amount of chlorine in the water and impede water flow. This can cause taste and discoloration issues and lead to reduced water flow for fire protection. Flushing helps remove this buildup to keep water clean, safe, and flowing.”
UDF flushing includes:
- Opening and closing water valves to isolate a specific section of water main
- Attaching a large hose to a specific fire hydrant and drawing water through to flush the isolated section of water main
- Draining flushed water into the City’s Stormwater infrastructure after chlorine has been removed
“Flushing water mains helps to extend their useful life,” said Kevin Meeuwsen, a Hillsboro Water Engineer. “Unidirectional flushing is a more effective way of cleaning than other flushing methods. UDF isolates each water main to create flow in a single direction to clean our main network quickly and efficiently.”
What Water Customers can Expect
Several days before flushing begins, signage will be posted in the immediate vicinity of the flushing area. During flushing, customers’ water service will not be disrupted, and customers can continue to use water.
Flushing may temporarily affect water pressure and stir up sediment in the pipeline, causing discolored water at customer’s taps. Although the discoloration does not pose a health risk, customers in the immediate flushing area are encouraged to:
- Avoid running the washing machine or dishwasher until flushing is complete
- Flush all taps for up to 10 minutes to clear the pipes after flushing is complete
- Unscrew and clean sediment from faucet aerators – or the small screens that are attached at the base of your kitchen or bathroom faucet spout – after flushing is complete
The UDF program is supported by Hillsboro Water’s current budget. Water rates and system development charges will not be increased to pay for the new UDF program.
UDF flushing will begin in the southeast area of the City. When crews complete flushing in this area, they will move to a new zone in the City. Flushing the more than 300 miles of water mains in Hillsboro Water’s service area is expected to take approximately three to four years. Flushing will occur Monday through Friday, between 8 am and 5 pm, throughout the year.
Additional information and a flushing area map are available at Hillsboro-Oregon.gov/Flushing.