Water hardness in Windsor (California)
7.7 gpg hard
Tap water in Windsor (California) is hard: 7.7 gpg (132 mg/L · 7.4 °dH · 13.2 °fH).
Source: California SWRCB Division of Drinking Water, EDT lab results, system CA4910017 (2026-03) · data checked 2026-10-19
Range across supply zones: 132–154 mg/L.
The Windsor figure comes from State Water Resources Control Board lab results for the Town of Windsor system. It rests on 3 well results from 2023 to 2026: a median of 132 mg/L as CaCO3 (7.7 gpg), with a range of 132 to 154 mg/L. The sample is small. The water is hard, so expect visible scale on kettles and heaters.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 7.7 gpg |
|---|---|
| Utility | Windsor, Town Of |
How Windsor (California) compares
- Tap water in Windsor (California) is 15 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 820 of 1372 in the United States (1 = hardest); 40 % of these cities have softer water.
- In California it is number 215 of 336 cities; the regional median is 9.5 gpg.
- Nearest city with clearly softer water: Sonoma, 41 km away (3.2 gpg).
- Nearest city with clearly harder water: Santa Rosa, 14 km away (9.7 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 Windsor
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 7 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| 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 Windsor (California) water hard or soft?
It is hard: 132 mg/L as CaCO₃ (7.7 gpg, 7.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Windsor (California) 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 Windsor (California) water?
7.7 gpg, equal to 7.4 °dH, 13.2 °fH or 132 mg/L calcium carbonate.
What dishwasher salt setting should I use in Windsor (California)?
For 132 mg/L (7.4 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Windsor (California)?
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 CA4910017 (2026-03). Method: own measurement. California SWRCB Division of Drinking Water, EDT lab results, system CA4910017 · Outdated figure? Tell us