Water hardness in Santa Monica
9.3 gpg hard
Tap water in Santa Monica is hard: 9.3 gpg (160 mg/L · 9 °dH · 16 °fH).
Source: California SWRCB Division of Drinking Water, EDT lab results, system CA1910146 (2026-07) · data checked 2026-10-19
Range across supply zones: 98–600 mg/L.
The Santa Monica figure comes from State Water Resources Control Board lab results for the city water division, using finished-water samples. The median of 91 results from 2021 to 2026 is 160 mg/L as CaCO3 (9.3 gpg), but results run from 98.1 to 600 mg/L. Raw well samples read higher and are treated before distribution, so the tap value is the finished one. This is hard water, and confidence in the exact figure is moderate.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 9.3 gpg |
|---|---|
| Utility | Santa Monica-City, Water Division |
How Santa Monica compares
- Tap water in Santa Monica is close to the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 664 of 1372 in the United States (1 = hardest); 51 % of these cities have softer water.
- In California it is number 171 of 336 cities; the regional median is 9.5 gpg.
- Nearest city with clearly softer water: San Gabriel, 38 km away (5.8 gpg).
- Nearest city with clearly harder water: Manhattan Beach, 14 km away (22.9 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Santa Monica
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 9 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| Hoover | S1 |
| LG | H2 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is Santa Monica water hard or soft?
It is hard: 160 mg/L as CaCO₃ (9.3 gpg, 9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Santa Monica safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
How many grains per gallon is Santa Monica water?
9.3 gpg, equal to 9 °dH, 16 °fH or 160 mg/L calcium carbonate.
What dishwasher salt setting should I use in Santa Monica?
For 160 mg/L (9 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Santa Monica?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: California SWRCB Division of Drinking Water, EDT lab results, system CA1910146 (2026-07). Method: own measurement. California SWRCB Division of Drinking Water, EDT lab results, system CA1910146 · Outdated figure? Tell us