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Wastewater

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Areal view of the Davis Wastewater Treatment Plant
Wastewater is water that has been impacted from ordinary living processes, including household, commercial, and industrial uses. It is essentially used water, containing materials and particles that would negatively impact people and the environment if left untreated. Wastewater entering a treatment plant is also called influent, and treated wastewater is called effluent.

Wastewater 101 document cover
Check out our Wastewater Utility 101 – an in-depth look at the City’s wastewater infrastructure and programs.

The City’s Wastewater Division operates and maintains the City’s wastewater system, supporting the residential, commercial, and industrial activities of the community. This includes the operation and maintenance of the collection system, treatment plant, and restoration wetlands, as well as the treatment of the wastewater generated in the Yolo County service areas of El Macero, North Davis Meadows, Davis Creek (formerly Royal Oaks) Mobile Home Park, and the Teichert Construction Complex.

As with most municipalities in California, the City of Davis wastewater collection and storm drain systems are separate. Wastewater flows to the wastewater treatment plant via the collection system and stormwater flows directly to local waterways, untreated.

image of a crewmember working on some sewer infrastructure. A white truck is parked nearby.

 The Collection System

The City’s wastewater collection system serves a population of about 70,717 people in Davis’ 10.5 square mile service area. The system serves 15,238 residential connections, and 50 commercial, industrial and institutional customers (as of 2019).
 
What makes up the Collection System?
  • 164 miles of gravity sewers (approximately 3,300 line segments) ranging in size from 6 to 66 inches in diameter – to transport the wastewater to the pump stations
  • 3,224 manholes – to provide access to sewer mains
  • 6 pump stations  - Davis’ wastewater collection system moves wastewater via gravity, and in certain areas of the City, there are pump stations to raise the wastewater higher so it can continue to flow via gravity to the wastewater treatment plant. By the time the wastewater piles reach the treatment plant, they are 40 feet below the surface.
  • 2.63 miles of force mains ranging in size from 4 to 14 inches – to transport the wastewater from the pump stations
  • Roughly 123 miles of sewer laterals – the piping from the sewer main to the building.