Portland's Water System
Portland's regional water system map.
Map shows Bull Run Watershed, water distribution areas, and the wellfield.
Mt. Tabor & Washington Park Reservoirs
Drinking water is stored in reservoirs on Mt. Tabor and Washington Parks
Powell Butte Reservoir & Nature Park
Powell Butte holds reservoirs underground and serve as a nature park.
Supplemental water is supplied from groundwater.
The Columbia South Shore Wellfield provides a reliable back-up supply.
Where does my tap water come from?
- Most of your tap water begins as rainfall in the Bull Run Watershed, located about 30 miles east of Portland.
- Despite its proximity to Mount Hood, none of Portland's drinking water originates from Mount Hood, as the watershed is separated from the mountain by a significant geologic ridge.
- Some water comes from the city's groundwater supply, which the bureau uses as a back-up supply.
How is my tap water treated?
- Bull Run water is not filtered.
- Chlorine is added to disinfect the water of any potential natural contaminants.
- Ammonia is added in a process called chloramination to ensure that water throughout the system meets federal and state drinking water regulations. Without ammonia the chlorine would evaporate by the end of the supply line..
How does my tap water travel to Portland?
- Water flows to Portland by gravity.
- Gravity flow reduces dependence on pumping and its expensive energy needs.
- Pumping is only required in the west hills of Portland, and for groundwater supplemental needs.
- The water travels through distribution mains to all parts of the city.
- Water mains run beneath sidewalks and streets to individual homes and businesses.
- From the water main, a smaller pipe travels to the water meter at each home or business that has water service.
- The water passes through the meter on its way to your home, which measures your household usage.
- Household pipes deliver water to your tap.
Who owns the water pipes and infrastructure?
- The Portland Water Bureau is a public utility.
- The mains and the water meter are generally owned by the City of Portland.
- Beyond the meter, household pipes are the responsibility of each property owner.
How much water is provided by the Portland Water Bureau?
Learn about Portland's primary drinking water source.
Seasonal supply augmentation and emergency back-up source.
Open storage reservoirs, not just pretty parks.
Powell Butte flows Bull Run to Portland
Tips for trouble shooting water flow and pressure issues
Facts on system infrastructure