San Diego Water Hardness & Quality Report (2026)
Water Hardness
10.1 grains per gallon
Source
mixed
pH Level
8.2
neutral = 7.0
Lead
0.009 mg/L
✓ Below action level
TDS
520.3 mg/L
Est. Daily Cost
$0.46
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 San Diego, your appliances are currently losing 23% efficiency due to mineral buildup.
| Appliance | In San Diego | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 3.9 yrs | 8.5 yrs | -54% |
| Washing Machine | 7.2 yrs | 12 yrs | -40% |
| Water Heater | 8.7 yrs | 15 yrs | -42% |
Regional Water Comparison
How San Diego compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ San Diego, California | 172.5 mg/L | 6.9 ppt | 🟠 Hard | mixed |
| Coronado, California | 138 mg/L | 5.9 ppt | 🟠 Hard | mixed |
| National City, California | 164.5 mg/L | 6.6 ppt | 🟠 Hard | mixed |
| Chula Vista, California | 126.5 mg/L | 5.5 ppt | 🟠 Hard | mixed |
| Lemon Grove, California | 165.5 mg/L | 6.7 ppt | 🟠 Hard | mixed |
National Benchmark
How San Diego compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ San Diego | 172.5 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes San Diego's Water Unique?
Local geology and source profile
San Diego is almost entirely dependent on imported water, receiving roughly 10% of its supply from local sources. The San Diego County Water Authority (SDCWA) imports water via two primary pipelines: the Colorado River Aqueduct, operated by the Metropolitan Water District of Southern California (MWD), which transports water from Lake Havasu on the Arizona border; and the State Water Project (SWP) California Aqueduct, carrying Sierra Nevada snowmelt from the Sacramento–San Joaquin Delta. The San Vicente Reservoir, El Capitan Reservoir, and Sweetwater Reservoir serve as regional storage facilities. This mixed-import supply is treated at the Skinner and Levy Water Treatment Plants before distribution throughout the county.
San Diego's hardness of 172.5 mg/L is driven primarily by its Colorado River import fraction. The Colorado River traverses hundreds of miles of Permian Kaibab Limestone and Carboniferous Redwall Limestone through the Grand Canyon corridor and Paleozoic carbonate formations of the Mojave Basin, collecting substantial calcium and magnesium carbonate ions throughout. The State Water Project water — sourced from Sierra Nevada granite snowmelt — is considerably softer, partially diluting the hard Colorado import. San Diego's position at the far end of the Southern California distribution chain means it receives a particularly high Colorado River proportion relative to northern California cities.
At the hard level, San Diego residents routinely notice white scale deposits on shower glass, faucet fixtures, and dishwasher interiors, along with reduced soap lather in laundry and bathing. The dry Southern California climate accelerates visible scale formation as water evaporates quickly on surfaces. Descaling showerheads monthly with a vinegar solution and fitting water heaters with a sacrificial anode rod are standard maintenance recommendations. A salt-based or template-assisted crystallization (TAC) water conditioner can significantly extend appliance and plumbing life.
Geology & Source: Colorado River imports cross Permian Kaibab Limestone; blended with softer State Water Project supply — hard at tap