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The City of Portland, Oregon

Portland Water Bureau

From forest to faucet, we deliver the best drinking water in the world.

Customer Service: 503-823-7770


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Century-Old Leaking Pipe Marks Beginning of Main Break Season

The Portland Water Bureau’s Maintenance & Construction crews are ready to respond to emergencies, including water main leaks and breaks, 24-hours a day, seven days a week. On average, crews respond to 200 main breaks a year, which is relatively low when compared to cities of similar size. We attribute this to our low-corrosive soil and proactive efforts to replace mains with the highest failure rates.

A leak on Monday, Sept. 19 shut down part of Northeast 33rd Avenue for approximately 24 hours and left more than 70 households without water during the repair. When crews excavated, they found a leaking connection on a 24-inch cast iron pipe installed in 1906. That’s more than a century old! Crews worked non-stop for more than 24 hours, restoring water service and re-opening Northeast 33rd Avenue well before the Wednesday morning commute.

What Does Our System Look Like?

This centenarian is unusual but not unheard of in our aging system. Approximately 20 percent of pipes with known ages in our system are 100-plus years old. However, the average age of our pipes is 64.

This repair on Northeast 33rd Avenue is an example of our proactive work. While replacing a leaking main, we took advantage of the excavation work and also replaced a nearby 24” valve that was installed in 1906.

In the last three years, the Water Bureau has completed an average of 300 hydrant replacements per year. In the last year, we installed almost five miles of new main, with contractors installing additional new main.  In the last year, we also installed or replaced 1,466 service and more than 400 valves. These are maintenance achievements that continue annually as part of our nationally recognized asset management program.

Some of the ways that we review our aging infrastructure are to:

  • Prioritize asset replacement if they are evaluated as high risk; 
  • Rank the replacement of old pipes based on the history of pipe breaks and other factors such as material and condition; 
  • Create a list of valves that are most in need of replacement based on the condition of the valve and the vital nature of the pipe;
  • Prioritize replacing hydrants that lack breakaway flanges or have galvanized or plastic service lines;
  • Prioritize many replacements based on what we learn from our condition assessments.    

Why Does a Main Break Occur?

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 flooding and property damage.

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.

Cooler temperatures 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..

Fixing Water Main Breaks
Every main break situation is different. The Water Bureau’s response will vary based on the specific situation. However, this is a general sequence of events that happen to fix a main break. 

  • The Water Bureau is notified of a possible water main break.
  • Urgent response personnel respond to the site to determine whether the leak is indeed a water main break.
  • If determined to be a water main break, valves are partially closed to reduce the flow of the water through the main, limiting any potential damage the water could cause.
  • The area is blocked off for safety and traffic is rerouted.
  • Other utilities, such as PGE and NW Natural Gas, are contacted to mark utilities lines that will help to ensure that excavating the break area in the street will not damage other services or endanger bureau staff or the public.
  • The Water Bureau repair crew brings in heavy equipment, including a backhoe, to excavate the site and expose the break.
  • The main break is assessed and crews determine how extensive the repairs will be.
  • Repair may require the crew to temporarily shut off water service to customers who are notified before their water service is turned off at the water meter.
  • The repair crew then cuts out and replaces the section of the damaged pipe.
  • The excavation is backfilled with rock.
  • The new main is flushed.
  • Water service is restored to the affected customers.
  • The repair crew ensures the backfilled excavation site is safe for traffic before removing the detour.
  • The Portland Bureau of Transportation completes the restoration of the street at a later date.

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.

Affected Customers – During & After 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. The discoloration does not pose a health risk. However, customers should avoid using hot water or running the washing machine or dishwasher until flushing is complete.

If you have experienced discoloration in your water, run the water at one tap for five minutes to see if it clears. If it does not clear, wait an hour and try again. When the water runs clear, flush any taps where discolored water was present. Take a look at our online Discolored Water fact sheet for additional information.

Reporting Water Main Breaks, Discolored Water
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 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.


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