Water Department City of San Diego
- Maintains and operates water lines, water treatment plants, pressure zones and offers public recreational use of its reservoirs. Sewer and water rates, and online bill paying information.
- http://www.sandiego.gov/water/

Olivenhain Municipal Water District
- Covers 48 square miles of North San Diego County, and is responsible for the operation of the Elfin Forest Recreational Reserve.
- http://www.olivenhain.com/

Sweetwater Authority
- Provides water for National City, Bonita and the western and central portions of Chula Vista.
- http://www.sweetwater.org/

Padre Dam Municipal Water District
- Information about local water service, quality and conservation, and about the Santee Lakes Regional Park.
- http://www.padredam.org/

San Diego County Water Authority
- Water wholesaler, created to administer the region's Colorado River water rights, import water and take over the operation of the aqueduct from the Navy. Site provides history, news, and education.
- http://www.sdcwa.org/

Otay Water District
- Public water and sewer agency serving communities of southeastern San Diego County
- http://www.otaywater.gov/

Helix Water District
- Serving the cities of La Mesa, El Cajon, Lemon Grove and unincorporated areas of San Diego County.
- http://www.hwd.com/

Bajagua Water Treatment Project, LLC
- Private company in charge of the wastewater treatment plant to be built in Mexico to treat sewage generated in Tijuana.
- http://www.bajagua.com