The City of Vacaville receives water from three sources for its drinking water:
- Surface water from Lake Berryessa, transported through Putah South Canal as part of the Solano Project.
- Surface water from the Sacramento Delta, transported through the North Bay Aqueduct as part of the State Water Project.
- Groundwater from ten wells located within City limits.
The percentage of water used from each source varies depending on the availability and quality of the water from each source.
The two surface water sources require treatment at water treatment plants prior to being put into the distribution system. Groundwater is treated at the wellhead and is then placed directly into the distribution system.