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 2,250 miles of water pipe in the city’s network, approximately 1,300 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. 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. Our response will vary based on the specific situation. However, in general, our crews fix a broken water main using the following steps:
Step one: Respond to the site of the leak. Reduce the flow of the water by turning control valves.
Step two: Request marking of gas, electric, and other utility lines so we can dig safely.
Step three: Cut open the road and dig down to the pipe.
Step four: Repair or replace the pipe.
Step five: Open a fire hydrant to pull clean water through the pipes, test water quality, then turn all the water back on.
Step six: Fill the hole and patch or put a plate on the street. Plan a permanent street repair.
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. Learn what to do during a discolored water event.
Reporting water main breaks and water quality issues
If you observe water running from streets or sidewalks, 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 you 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.
Prepare your own plumbing for winter weather
Pipe breaks of all kinds are more common during cold weather, and your household pipes are no exception. You can take steps to protect your own plumbing from winter weather to reduce the risk of breaks.