Our protected drinking water sources
Portland is fortunate to have two high-quality drinking water sources, the Bull Run Watershed and the Columbia South Shore Well Field. We work diligently to protect these essential resources and deliver drinking water that meets or surpasses all federal and state drinking water standards.
Treating our drinking water
Portland’s drinking water is treated to produce high-quality drinking water that meets all state and federal drinking water regulations. Currently, drinking water treatment is a three-step process:
- Chlorine disinfects against organisms, such as bacteria, Giardia, and viruses, that could otherwise make people sick.
- Ammonia stabilizes chlorine to form a longer-lasting disinfectant.
- Sodium carbonate and carbon dioxide reduces corrosion of metals like lead.
Portland’s treatment is changing in the coming decade. Starting in 2027, Bull Run water will be filtered to treat for Cryptosporidium.
Testing our drinking water
We test for more than 200 regulated and unregulated contaminants in our drinking water. We collect samples from across the entire system, including the water sources, the in-town distribution system, and some residents’ homes. Water quality testing allows us to monitor the effectiveness of disinfection and treatment so that we continue to meet regulations to protect public health.
We are required to meet both federal water quality standards and state water quality standards. We report our test results to the state as required and share results on our website.
Find drinking water test results
Want to test your own water? We have a free lead-in-water testing program. Request a test kit today.
Maintaining our drinking water quality
After we treat the water, we work hard to maintain drinking water quality throughout the city. Our certified operators fix and prevent issues in the drinking water system to keep safe water flowing.
One tool we use to maintain water quality is hydrant flushing. Hydrant flushing is a technique used across the country to maintain water quality and clean the pipes that deliver water to homes and businesses. When we flush water through hydrants, we flush material out of the mains and bring fresh water into them.
You also have a role to play in maintaining the drinking water quality in your home or business. Learn more in our water quality and pressure troubleshooting guides or large building water quality page.