The Portland Water Bureau began constructing our water system in 1893, and it has only grown larger and more complex since then. Today, our water system delivers over 30 billion gallons of high-quality water each year to about 1 million people in Portland and the surrounding areas. On average, we deliver enough water to fill up 144 Olympic-size swimming pools every day! (That’s 95 million gallons, for those keeping track at home.)
Serving that much water takes more than 2,250 miles of pipes, nearly 15,000 hydrants, 54 tanks and covered reservoirs, 36 pump stations, over 60,000 valves, 192,000 water meters, and more than 600 employees. Since many parts of our water system are very old, we complete thousands of projects each year to replace outdated components. That keeps us busy around the clock as we operate, maintain, and improve our water system so we can continue to move high-quality drinking water from our water sources to taps throughout the Portland area.
Water from above and water from below
Our drinking water comes from two excellent sources, which we carefully monitor and protect. These two special water sources work together to keep Portland-area residents supplied with delicious, high-quality drinking water.
Bull Run Watershed
Most of your tap water begins as rainfall in the Bull Run Watershed, located about 30 miles east of Portland in Mount Hood National Forest. The Bull Run is a lush temperate rainforest, home to numerous plants and animals and an abundance of water. Thanks to decades of hard work and advocacy by city residents and leaders, federal and local laws limit human activities in the watershed and protect the quality of our drinking water.
Columbia South Shore Well Field
The Columbia South Shore Well Field is a high-tech groundwater system that includes more than 20 active wells. Our ongoing investments in this secondary water source help us keep excellent water flowing to Portlanders year-round—even in high-demand summer months or during unexpected events in the watershed.
Water's journey from the source to your tap
After our water leaves the source, it moves through a complex network of treatment facilities, reservoirs, pipes, and valves before reaching your tap. Along the way, our staff manage the flow of water throughout the system and maintain its excellent quality.
Stop 1: Drinking water treatment
After leaving the Bull Run Watershed, our water makes its first stops at our treatment facilities. Water from the Columbia South Shore Well Field is treated onsite at our central groundwater pump station.
Stop 2: Powell Butte reservoirs
Most pipes in Portland connect to two large, concrete reservoirs buried underground at Powell Butte Nature Park. With a higher elevation than most of the city, Powell Butte is the perfect location to store drinking water and use gravity to move it throughout the city’s vast system of reservoirs, tanks, and pipes to the faucets in your home.
The power of gravity also brings water to Powell Butte from our Bull Run treatment facilities. Massive (up to five and a half feet wide!) pipes called conduits carry water for miles from the watershed to these in-town reservoirs. When groundwater is in use, powerful pumps push the water uphill for five miles to reach Powell Butte, where it can be blended with water from Bull Run.
Each reservoir at Powell Butte can hold up to 50 million gallons of water and has an area the size of four football fields and a height of three stories! All that water gives us time to adapt to unexpected events or variations in water use without interrupting water service.
Stop 3: Other reservoirs: Washington Park and Kelly Butte
Powell Butte also feeds other, smaller reservoirs that store water in town. Just down the road, the Kelly Butte Natural Area houses an underground reservoir that holds 25 million gallons of water and provides water directly to customers throughout the east side of Portland.
Over on the west side of Portland, a new 12.4-million-gallon underground reservoir at Washington Park supplies water to more than 360,000 people. Completed in 2021, the new reservoir replaced reservoirs originally built in the 1890s and is designed to withstand a major earthquake.
Washington Park Reservoir is the Powell Butte of the west side—a central hub that distributes water throughout the west side. Gravity brings water across the Willamette River and then to the Washington Park Reservoir. From there, water either flows downhill to homes and businesses in downtown Portland or is pumped to smaller water tanks at even higher elevations before heading to customers throughout the west hills.
Detour: Mount Tabor Reservoirs
For many years, the three open reservoirs at Mount Tabor Park played a key role in Portland’s water system. However, due to changing federal requirements, the reservoirs were disconnected from the system in 2015 and no longer store or provide drinking water. We still maintain the reservoirs to preserve the historic and aesthetic character of the park.
Stop 4: Storage tanks
From the reservoirs at Powell Butte, Kelly Butte, and Washington Park, large pipes called mains move water throughout the city to a network of smaller storage tanks. Most of our storage tanks can hold between 40,000 and 4 million gallons of water each. Combined, all our in-town reservoirs and tanks can hold more than 200 million gallons of water, enough to meet our water needs for about two days.
Water storage tanks have two primary functions. First, with their higher elevation, the tanks improve and maintain pressure throughout the system. Our water system needs the right amount of water pressure to deliver water to customers and maintain water quality. Second, water tanks ensure that there is enough water supply throughout the city to fight fires.
Water does not sit or stagnate in the tanks but rather flows through them continuously. Control center operators at the Water Bureau monitor the flows and levels in the tanks nonstop to make sure that the water reaching customers’ faucets is clean, cold, and fresh. Every five years, we drain, clean, and inspect each tank and perform any needed repairs. Regular cleaning and maintenance keep our tanks in good condition and help maintain excellent water quality throughout our system.
Stop 5: Your tap
Water mains ranging in diameter from less than six inches to over 24 inches carry water from storage tanks to taps around town. Maintaining more than 2,250 miles of pipe is no easy feat! We do everything from cleaning our pipes to responding quickly to breaks. Our pipes have an average age of around 70 years, and almost one-quarter were installed before 1930. Because many of our pipes are reaching the end of their useful lives, we replace over 30,000 feet of pipe each year!
Thousands of valves connect the pipes in our system, helping to maintain water pressure and allowing us to control the flow of water during maintenance and repairs. We regularly exercise our large valves to ensure they work when we need them.
From the water main, a smaller pipe travels to the water meter at each home or business. On its way to your tap, the water passes through the meter, which measures your water usage. Household pipes deliver water to your tap. The Portland Water Bureau owns and maintains all the pipes up to and including the water meter. Beyond the meter, the property owner is responsible for maintaining the service line and household pipes. The age and condition of household plumbing can impact water quality at your tap. If you experience water quality or pressure issues at your tap, our Water Quality Line can help you troubleshoot the issue
Working for water
Our 600-plus employees are a crucial part of our water system. Keeping this complex system operating requires us to work all night, on weekends, and on holidays. We’re constantly focused on maintaining our water system, keeping your water safe, and preparing our system for the future.