Antioch Water Hardness & Quality Report (2026)
Water Hardness
7.8 grains per gallon
Source
mixed
pH Level
7.9
neutral = 7.0
Lead
0.007 mg/L
✓ Below action level
TDS
370.2 mg/L
Est. Daily Cost
$0.36
energy & soap waste
Source: USGS Water Quality Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Antioch, your appliances are currently losing 18% efficiency due to mineral buildup.
| Appliance | In Antioch | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 5.2 yrs | 8.5 yrs | -39% |
| Washing Machine | 8.7 yrs | 12 yrs | -28% |
| Water Heater | 10.3 yrs | 15 yrs | -31% |
Regional Water Comparison
How Antioch compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Antioch, California | 133.5 mg/L | 5.9 ppt | 🟠 Hard | mixed |
| Pittsburg, California | 128 mg/L | 5.7 ppt | 🟠 Hard | mixed |
| Oakley, California | 145 mg/L | 6.2 ppt | 🟠 Hard | mixed |
| Brentwood, California | 51 mg/L | 3.5 ppt | 🟢 Soft | mixed |
| Bay Point, California | 119.5 mg/L | 5.5 ppt | 🟡 Moderately Hard | mixed |
National Benchmark
How Antioch compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Antioch | 133.5 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Antioch's Water Unique?
Local geology and source profile
Antioch, California, on the south bank of the Sacramento–San Joaquin Delta in eastern Contra Costa County, draws its municipal water supply primarily through the City of Antioch Water Division and the Contra Costa Water District (CCWD), sourcing directly from the Sacramento–San Joaquin Delta via CCWD's Delta intake facilities near Antioch and from the Los Vaqueros Reservoir in eastern Contra Costa County. CCWD also treats raw Delta water at the Bollman Water Treatment Plant in Concord. The Delta at the Antioch reach blends Sacramento River (fresher, Sierra Nevada-sourced) and San Joaquin River (more mineralised, Central Valley-sourced) water. Water hardness measures 133.5 mg/L — classified as moderately hard.
Antioch's moderate hardness reflects the Delta's blended source water character at the eastern San Francisco Bay margin. The Delta receives Sacramento River water (primarily soft Sierra Nevada granite snowmelt) and San Joaquin River water — the San Joaquin and its tributaries draining the Diablo Range (Franciscan Complex greenstone, chert, and calcareous marine sediments — Cretaceous Great Valley Sequence calcareous turbidites) and the Sierra Nevada foothills contribute significant dissolved calcium. CCWD's Los Vaqueros Reservoir stores and blends these sources. The Antioch distribution zone's hardness is slightly higher than Concord (97 mg/L) on the same CCWD system, reflecting the proximity to the higher-mineral-content eastern Delta source water.
At 133.5 mg/L, Antioch residents encounter moderate scale accumulation. Faucet aerators and showerheads develop deposits after several months — monthly cleaning with citric acid solution is practical maintenance. Dishwashers produce cleaner glassware with rinse-aid. Contra Costa Water District consistently delivers water meeting all California SWRCB and EPA Safe Drinking Water Act requirements.
Geology & Source: Mixed supply from the Sacramento–San Joaquin Delta via the Contra Costa Water District (CCWD) Delta Pumping Station and Los Vaqueros Reservoir — the Delta at Antioch receives Sacramento River (Sierra Nevada snowmelt) and San Joaquin River (coastal calcareous runoff) blends; Diablo Range calcareous Franciscan marine sediments in the CCWD watershed contribute moderate hardness at 133.5 mg/L.