Water Treatment Process

Hillsboro Water Resource Recovery Facility

The Hillsboro Water Resource Recovery Facility, located between Jackson Bottom Wetlands and downtown Hillsboro, is a nationally acclaimed, state-of-the-art facility serving the cities of Hillsboro, Cornelius, and Banks. Considered one of Clean Water Services’ smaller facilities, it is part of a larger treatment system through its connection to the Forest Grove and Rock Creek facilities.

Today, the facility cleans an average wet-weather flow of 6 million gallons each day to among the highest safety and quality standards in the nation as water flows through a strategic process of liquids and solids recovery. The liquids treatment processes include screening, grit removal, primary clarifiers, and advanced biological activated sludge process, secondary clarifiers, and disinfection using ultraviolet light (UV). The water is returned to Washington County’s only river — the Tualatin. The returned water is so clean, it improves the river’s water quality.

During dryer months, the flow undergoes preliminary and primary treatment processes. Then, the liquid flow is pumped to Forest Grove for additional treatment. Solids removed from the Hillsboro facility are pumped to the Rock Creek facility for treatment.

The Hillsboro facility was constructed in 1969 and significant modifications and upgrades were completed in 2014 to meet the demands of a growing population and increasing regulatory requirements.

Hillsboro water resource recovery facility aerial View

Hillsboro Water Resource Recovery Facility Process

Used water flows through a series of processes (PDF): preliminary, primary, secondary, disinfection, and effluent discharge.

Hillsboro Facility Facts

  • Provides a higher level of treatment over many activated sludge systems, as it utilizes biological phosphorus and nitrogen removal
  • Operates 24-hours a day, 365 days a year
  • Meets over 1,000 permit conditions, including monthly, weekly, and daily limits establish to protect the Tualatin River
  • Cleans an average of approximately 6 million gallons of wastewater per day
  • Takes advantage of resource sharing by utilizing the Rock Creek facility for solids treatment
  • National Association of Clean Water Agencies (NACWA) Awards over multiple years