How main breaks happen
A main break occurs when the water main develops a crack or a hole that lets water out into the surrounding soil. On the surface, main breaks can look like leaks bubbling up out of the street, and, in extreme cases, the water can cause sink holes and flooding.
In Portland, cast iron water mains tend to break during the colder times of the year. Of the 2,100 miles of water pipe in the city’s network, approximately 1,350 miles are cast iron pipe. The majority of these cast iron pipes were installed before 1960 and remain in the water system.
Cold water can cause pipes to become more brittle. Adding cold air temperatures at or below freezing can cause the ground above a pipe to freeze and thaw, thereby increasing external stress on a pipe. Temperatures can be just one factor in causing a main break. The age of a pipe, soil conditions, pipe corrosion, and ground movement can also cause a main to weaken over time and break.
Fixing water main breaks
Every main break situation is different. The Water Bureau’s response will vary based on the specific situation. However, this graphic shows a general sequence of events that happen to fix a main break. A simple water main repair can be completed in six to eight hours, but large or complicated repairs may take several days to a week.
Find a text version of the graphic at the bottom of this page.
During and after a main break
During a main break, customers in the immediate vicinity may notice a reduction in water pressure or have their water temporarily shut off while repairs are being made. Customers may also experience discolored water. This color is from sediment that is always in our pipes and can get stirred up during a main break. Visit our discolored water page for more information and find steps to take.
Reporting water main breaks and water quality issues
Anyone observing water running from streets or sidewalks is encouraged to report the leak to the Water Bureau. Please call the Water Bureau’s 24-hour Emergency Line at 503-823-4874 for water system emergencies, including suspected main breaks.
If customers experience ongoing water quality problems or lost water service with no notification, call the Water Quality Line at 503-823-7525, Monday through Friday, between 8:30 a.m. and 4:30 p.m. After hours, contact the 24-hour Emergency Line at 503-823-4874.
How our crews fix a main break (text version)
- Respond to the site of the leak. Reduce the flow of the water by turning control valves. [Illustration of two construction workers standing in a puddle from the main break and working together to turn a handle to close the valve.]
- Request marking of gas, electric, and other utility lines so we can dig safely. [Illustration of a utility worker using paint to mark the road near the main break.]
- Cut open the road and dig down to the pipe. [Illustration of a backhoe next to a square hole in the road. In the hole is the broken pipe surrounded by dirt and water.]
- Repair or replace the pipe. [Illustration of two construction workers guiding a new pipe into the hole in the road.]
- Open a fire hydrant to pull clean water through the pipes, test water quality, then turn all the water back on. [Illustration of a construction worker next to an orange fire hydrant that has water flowing out of it.]
- Fill the hole and patch or put a plate on the street. Plan a permanent street repair with the Portland Bureau of Transportation. [Illustration of a construction worker spreading fresh asphalt with a rake and a steam roller flattening the new asphalt.]