Plumber in Lake Oswego, OR: sewer laterals, backflow and hiring

Census Bureau survey data for 2020 to 2024 put Lake Oswego's median year built at 1982. About 46 percent of homes were built before 1980, about 13 percent before 1960 and about 20 percent in 2000 or later (ACS table B25034 via Census Reporter). Two city programs matter most to owners: sewer lateral responsibility and annual backflow testing.

The city's water department page says Lake Oswego draws water from an intake on the Clackamas River in Gladstone and treats it at a plant in West Linn shared with Tigard, which produces water for more than 100,000 customers. As of spring 2025, 99 percent of the city's 12,630 meters had been replaced with wirelessly read smart meters, which makes unusual use easier to spot on your bill. The 2026 water quality report states that the system has no known lead pipes or connections, that the main source of lead is household plumbing or components on the back side of the meter, and that the city offers free lead testing to its water customers.

The city's sewer laterals page describes the lateral as the 3 or 4 inch pipe carrying waste from the home to the city's 8 to 36 inch collection system. The split works like this:

If a camera inspection during a home sale shows a problem in the right of way, the city asks you to contact Public Works Maintenance and provide the video for review. It also says no private contractor should dig up or repair any part of the lateral in the right of way without notifying the city and getting permission and permits. A property line cleanout, a 4 inch capped pipe usually just behind the curb or sidewalk, makes clearing and camera work easier; ask a plumber whether yours has one. After hours, the city's sewer page lists LOCOM at 503-635-0238 for sewer overflows and backups.

The city maintains 206 miles of collection pipe and 13 major pump stations, all flowing to the Tryon Creek treatment plant operated by the City of Portland. Lake Oswego is replacing that aging 1964 plant with a new facility. Our tree roots guide explains why mature yards often mean root-clogged laterals.

The backflow and cross connection control program applies to homes with irrigation, hot tubs, pools or private wells. Key points:

• A backflow prevention assembly must be tested once a year by a state-certified tester, with results submitted by July 15.
• A device that fails must be repaired and retested.
• Irrigation systems using atmospheric or pressure vacuum breakers that need more than normal repairs must switch to approved double-check assemblies.
• Testers who charge a fee need a CCB or Landscape Contractors Board license, and the city says it has not verified licenses on its tester list.

That last point is a good habit for any hire: check the license yourself rather than relying on a list.

Oregon splits plumbing licensing between two agencies. The Construction Contractors Board (CCB) licenses the business, and the Building Codes Division (BCD) licenses plumbing contractors and individual journeyman plumbers. Run both checks before you sign anything:

1. Search the company in the CCB license search and confirm the license is active.
2. Search the company and the person doing the work in the BCD license holder search.
3. Ask who pulls the plumbing permit, and get the permit number before work starts.

Our guide to choosing a plumber explains the two licenses in more detail, and the Portland plumber cost guide helps you judge a quote.

This site is an independent guide, not a contractor. We do not perform plumbing work and do not answer phones. To reach a plumber, call one of the licensed contractors listed on this page or see all listed contractors. Questions about this guide: email us. We do not take service requests. If water is actively leaking, shut off the main valve first and see our emergency plumber guide.