The water district serves two-thirds of Los Altos Hills and unincorporated Santa Clara County with water from the…More Hetch Hetchy Reservoir in the Sierra Nevada. The city of San Francisco, which owns the reservoir and the distribution, sells that water to the Purissima Hills Water District. The district grew from about 350 customers when it was founded in 1955 to more than 6,400 in 2010.
Most of the water district's customers are single family households, but the largest customer is Foothill College. The district itself has not been under mandatory water rationing the way many districts have, but the city of San Francisco has asked for a 10 percent voluntary reduction from all of its water district customers. Long-needed infrastructural improvements to the nearly 100-year-old system will result in rate increases in the near future.
The five-member water district board is elected and meets at 6:30pm every second Wednesday of the month.