Wastewater Services

The City of Modesto offers tech-forward services to recycle contaminated water from homes and businesses into purified and treated water that is safe for environmental use.


The Collections department ensures that wastewater flows from homes and businesses through a network of underground pipes to the City’s treatment facilities. They maintain the wastewater pipes in the street, perform necessary maintenance to keep the water flowing, and handle customer service along the way.

If requested, they can provide a complimentary lateral cleaning and inspection of your home’s lower lines in the street to verify that your wastewater is flowing unobstructed through your pipes to the City’s wastewater pipelines.


The Operations department receives and treats the wastewater to meet stringent effluent requirements mandated by the State of California so that it is safe to be returned to the environment.

In order to make the wastewater safe for various agricultural and environmental uses, it goes through preliminary, primary, secondary, and mainly tertiary treatment, depending on its designation.


The Maintenance department ensures that all wastewater equipment is well-maintained and functional for continuous service. This includes pumps, motors, all electrical, chemicals, and the inner workings of each treatment facility.

Environmental Compliance

Environmental Services is committed to ensuring a more vibrant community. To keep the City’s wastewater safe for eventual reuse in irrigation, the department inspects and monitors the discharge from businesses and industries that goes into the sanitary sewer.

They also inspect and monitor compliance with the City’s Stormwater Permit to prevent the pollution of urban stormwater. Environmental Services uses an in-house State-certified laboratory to analyze samples of the Tuolumne River and Dry Creek.

Wastewater Facilities

The City of Modesto owns and operates two wastewater treatment facilities: Sutter and Jennings. Modesto’s wastewater is treated to meet the stringent Federal and State regulatory requirements. An average of 20 million gallons of Modesto’s wastewater is treated per day at Sutter, and nearly 15 million of those gallons are further treated at Jennings to tertiary (recycled water) levels.

Additional Programs

The City has two programs to help save you money: the Call Us First program and the Cost Share Program.

  • The Call Us First program encourages residents to call Wastewater Services at 209-577-6200 before calling a plumber to see if they can resolve your problem for free.
  • The Cost Share Program offers financial assistance to residents if repairs or maintenance is required for the sewer line in the public right-of-way.
Two City workers clean a digester at the Sutter Treatment Plant