Thousand Oaks Water Hardness & Quality Report (2026)
Water Hardness
11 grains per gallon
Source
mixed
pH Level
8.3
neutral = 7.0
Lead
0.01 mg/L
✓ Below action level
TDS
590.9 mg/L
Est. Daily Cost
$0.50
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 Thousand Oaks, your appliances are currently losing 25% efficiency due to mineral buildup.
| Appliance | In Thousand Oaks | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 3.4 yrs | 8.5 yrs | -60% |
| Washing Machine | 6.6 yrs | 12 yrs | -45% |
| Water Heater | 8.1 yrs | 15 yrs | -46% |
Regional Water Comparison
How Thousand Oaks compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Thousand Oaks, California | 188 mg/L | 7.4 ppt | 🔴 Very Hard | mixed |
| Agoura Hills, California | 32.5 mg/L | 2.8 ppt | 🟢 Soft | mixed |
| Oak Park, California | 138.5 mg/L | 5.9 ppt | 🟠 Hard | mixed |
| Agoura, California | 32 mg/L | 2.8 ppt | 🟢 Soft | mixed |
| Simi Valley, California | 109 mg/L | 5.1 ppt | 🟡 Moderately Hard | mixed |
National Benchmark
How Thousand Oaks compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Thousand Oaks | 188 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Thousand Oaks's Water Unique?
Local geology and source profile
Thousand Oaks, California, in eastern Ventura County at the Conejo Valley, receives its municipal water supply through the Calleguas Municipal Water District (CMWD) and the City of Thousand Oaks Water Services, sourcing from two origins: State Water Project (SWP) Delta water delivered via the East Branch of the California Aqueduct and the Calleguas Pipeline System from Castaic Lake in Los Angeles County; and local Conejo Valley groundwater from the Mugu and Conejo alluvial basin aquifers in Ventura County. CMWD is the primary regional water wholesale agency for most of Ventura County. Water hardness in Thousand Oaks measures 188 mg/L — classified as hard.
Thousand Oaks' hard supply primarily reflects the character of the State Water Project water delivered via the Calleguas system. SWP water originates from Sacramento–San Joaquin Delta exports blending Sacramento River runoff (draining the Sierra Nevada) and San Joaquin River runoff (draining the Sierra Nevada and Coast Ranges). By the time SWP water reaches southern California through the Delta–Mendota Canal and California Aqueduct, it has traveled hundreds of miles through calcareous San Joaquin Valley terrain and accumulated significant mineral content. Local Conejo Valley groundwater from the Conejo Volcanics (Miocene basalt and andesite) and Franciscan Complex-derived alluvial fill contributes additional dissolved calcium to the blended supply.
At 188 mg/L, Thousand Oaks residents encounter regular hard water challenges. Calcium deposits form on faucet aerators, showerheads, shower glass, and tile within weeks — monthly descaling with citric acid solution is a standard maintenance routine. Dishwashers produce better glassware results with rinse-aid, and water heaters benefit from annual inspection for element scale accumulation. Calleguas Municipal Water District and City of Thousand Oaks Water Services consistently deliver water meeting all California SWRCB and EPA Safe Drinking Water Act requirements.
Geology & Source: Mixed supply from State Water Project deliveries via the Calleguas Municipal Water District (CMWD) and local Conejo Valley groundwater — SWP Delta water blended with Calleguas Creek Mugu Aquifer and Conejo Creek alluvial basin groundwater — Coast Range Franciscan Complex and Conejo Volcanics watershed geology produces moderately hard supply at 188 mg/L due to high SWP import fraction.