Pittsburg Water Hardness & Quality Report (2026)

Pittsburg, California, in eastern Contra Costa County on the Sacramento–San Joaquin Delta at the southern end of Suisun Bay — a former steel mill town now a commuter community — draws its municipal water supply from the Sacramento–San Joaquin Delta via the Contra Costa Water District (CCWD), which treats Delta water at the Ralph D. Bollman Water Treatment Plant in Concord and stores water in the massive Los Vaqueros Reservoir (off-stream Delta water storage facility in eastern Contra Costa County). Water hardness in Pittsburg measures 128 mg/L — classified as moderately hard.

Pittsburg's moderate hardness reflects the Contra Costa Water District's Delta supply blend. The Sacramento–San Joaquin Delta water at the CCWD intake blends: the relatively soft Sacramento River water (from the Sierra Nevada); the moderately hard San Joaquin River water (from the Sierra Nevada but with Central Valley agricultural drainage contribution); and Delta agricultural drainage (which concentrates dissolved minerals from the calcareous soils of the Sacramento–San Joaquin Delta islands). The CCWD's Los Vaqueros Reservoir serves as a quality storage buffer — capturing the best-quality Delta water when available. The blend of Sacramento, San Joaquin, and Delta sources produces the 128 mg/L moderate hardness at Pittsburg.

At 128 mg/L, Pittsburg residents encounter moderate scale accumulation. Faucet aerators and showerheads develop deposits after several months — monthly cleaning with citric acid solution is practical maintenance. Contra Costa Water District consistently delivers water meeting all California SWRCB and EPA Safe Drinking Water Act requirements.