Sanitary Sewer

The Cornelius Sanitary Sewer Division provides sanitary wastewater services for all houses and buildings in the city by operating and maintaining 35 miles of sanitary sewerage facilities. We provide this service at the best rates possible while fully complying with the wastewater management requirements of Clean Water Services (CWS).

Sanitary Sewers vs. Storm Sewers Unlike some of the older antiquated cities, Cornelius does not have a combined sanitary and storm system; our storm system is completely separate from our sanitary sewer system. Water and waste products from your toilet, shower, dishwasher, and sink go into the sanitary sewer system for treatment prior to discharge to the Tualatin River.

Rainwater running off your roof and the city streets goes into the storm drainage system and then directly to the Tualatin River. Therefore, it is very important not to rinse or dump anything into the street drains.

Clean Water Services 
Clean Water Services (CWS) is a county special service district formed in 1970 that provides sanitary sewer and surface water management utility services in portions of Washington, Multnomah and Clackamas Counties. CWS's mission is to provide cost-effective services and environmentally sensitive management of water resources for the Tualatin River watershed.

(In Cornelius, city crews maintain all the underground piping for the sanitary sewage and storm drainage systems. CWS provides sewage treatment at their treatment plant in Forest Grove.)

Sewer Blockages 
Before contacting a plumber or sewer service, call Public Works at 503-357-3011 and an employee will be sent out to determine the location of the blockage at no charge to you. If it is determined that the blockage is not in the City's mainline, the customer is responsible for removing the blockage at their own expense.

FOG - Fats, Oils, and Grease
Improper disposal of fats, oils, and grease is a major cause of sewer blockages.  Severe blockages can lead to sewer overflows which can cause health hazards, damage homes, and threaten the environment.  For more information on preventing blockages by proper disposal of household fats, oils and grease, click on the link below.