Water Facts in CA


Who uses how much? California water by the numbers

County     Gallons per capita per day

San Francisco     108.4 (the lowest, by far)
San Mateo         133.4
Marin                154.8
Contra Costa     172.0
Alameda           173.9
Napa                184.5
Los Angeles      185.0
Sacramento       260.9
Mono                471.6 (highest)


Marin Watershed Water Supply Update

North Bay

Local reservoirs and streams and groundwater are the major sources of supply for cities such as Mill Valley, Santa Rosa, Vacaville, Fairfield and Clearlake. The State Water Project’s North Bay Aqueduct supplies Napa and Solano counties.


GroundwaterAbout 30 percent of California’s total annual water supply comes from groundwater in normal years, and up to 60 percent in drought years. Local communities’ usage may be different; many areas rely exclusively on groundwater while others use only surface water supplies. Contrary to popular opinion, groundwater does not exist in underground lakes. Groundwater fills pores (spaces) between sand, gravel, silt and clay in water-bearing formations known as aquifers.






Pie chart showing indoor water usage. Shower: 16.8% Toilet: 26.7% Faucet: 15.7% Clothes washer: 21.7% Leaks: 13.7% Other: 5.3%

The bathroom is the largest consumer of indoor water. The toilet alone can use 27 percent of household water. Almost every activity or daily routine that happens in the home bathroom uses a large quantity of water.

For example:

  • Older toilets use between 3.5 and 7 gallons of water per flush. However, WaterSense labeled toilets require 75 to 80 percent less water.

Outside the bathroom, there are many opportunities to save water. Here are some common water efficiency measures, along with a few solutions to those problems you may not have known existed:

  • High-efficiency washing machines can conserve large amounts of water. Traditional models use between 27 and 54 gallons of water per load, but new, energy- and water-conserving models (front-loading or top-loading, non-agitator ones) use less than 27 gallons per load.


What is a Watershed?




pictorial display of a watershed
Navarro River Watershed Report 2013

Hydroelectric System

PG&E’s hydroelectric system provides Californians with safe, reliable and clean energy from a renewable resource. The largest investor-owned hydroelectric system in the nation, its history dates back to the days of California’s Gold Rush.

Simply put, hydroelectricity is generated by the force of falling water. A series of dams and reservoirs on river basins collect water. The water is then directed through large pipes (called penstocks) to turbines that spin generators to create electricity.

Fast Facts

  • Water used to power the hydroelectric system comes from more than 100 reservoirs located mostly in the higher elevations of California’s Sierra Nevada mountain range.
  • Our 68 powerhouses have a total generating capacity of 3,896 megawatts, which is enough power to meet the needs of nearly 4 million homes


1 thought on “Water Facts in CA

  1. I am pretty surprised that Sacramento uses way more water than Los Angeles or San Francisco. However, I know that water is pretty restricted throughout the state and so do you know why so much water is used in that area? I would suppose that it has to do with local farms, but I am not too sure.


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