Treatment Requirements

In California, our water is treated under the State Department of Health Services requirements as specified in Title 17 and Title 22 of the California Health and Safety Code and Chapter 7 of the California Safe Drinking Water Act. The State requires the District to periodically test the water and report the results to its customers.

Our water is taken from the Cosumnes River at Granlees Dam and pumped into Calero, Chesbro and Clementia Reservoirs from November 1 until May 31 of each year. The stored water is used throughout the year for the needs of the community. These Reservoirs work as large settlement basins before the water is transferred to the Water Treatment Plant at the foot of the Chesbro Reservoir Dam.

Treatment Process

In the early 1970’s, the first treatment facilities consisted only of chlorination of raw water for disinfection. In 1978, a 1.5 million gallons per day (mgd) capacity Surface Water Treatment Facility (SWTF) was constructed to meet the increased demands of development at the time and upgraded treatment requirements.

In 1987, a duplicate plant with 2.5 mgd capacity was constructed. Both conventional treatment plant processes were comprised of coagulation, flocculation, sedimentation, followed by filtration and finally disinfection. Both of these plants were retrofitted in 1995 to meet the new Surface Water Treatment Rules, changing from single media sand filters to dual media sand and anthracite filters, at which point Plant 2 was de-rated from 2.5 to 2.0 mgd due to hydraulic constraints. 

In 2014-2016, to meet the increasing demands of new homes, Plant 1 was retro-fitted to become a nominally rated 4.0 mgd ultrafiltration submerged membrane facility.