Water hardness in Palo Alto
11.4 gpg very hard
Tap water in Palo Alto is very hard: 11.4 gpg (195 mg/L · 10.9 °dH · 19.5 °fH).
Source: California SWRCB Division of Drinking Water, EDT lab results, system CA4310009 (2025-09) · data checked 2026-10-19
Range across supply zones: 95–340 mg/L.
The Palo Alto figure comes from State Water Resources Control Board lab results for the City of Palo Alto system. The median of 6 well results from 2022 to 2025 is 195 mg/L as CaCO3 (11.4 gpg), with a range of 94.5 to 340 mg/L. The sample is small and the spread is wide. On median, the water is very hard.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 11.4 gpg |
|---|---|
| Utility | City Of Palo Alto |
How Palo Alto compares
- Tap water in Palo Alto is 26 % harder than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 540 of 1372 in the United States (1 = hardest); 60 % of these cities have softer water.
- In California it is number 130 of 336 cities; the regional median is 9.5 gpg.
- Nearest city with clearly softer water: Sunnyvale CA, 10 km away (5.7 gpg).
- Nearest city with clearly harder water: Los Altos, 5 km away (18.1 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Severe scale: heater elements and washing-machine heaters fail early.
- Detergent use is very high; taps and screens coat within days.
- Dishwasher at maximum salt setting.
- An ion-exchange softener is practically essential; RO for drinking water.
How much salt will you use for softening?
Yes. At this hardness a softener pays for itself through appliance life and detergent.
Descale a coffee machine or kettle about every 1 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Palo Alto
| Brand | Setting for this water |
|---|---|
| Bosch | H03 |
| Miele | 11 °dH |
| AEG / Electrolux | 3 |
| Beko | 3rd |
| Hoover | S2 |
| 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 Palo Alto water hard or soft?
It is very hard: 195 mg/L as CaCO₃ (11.4 gpg, 10.9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Palo Alto 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 Palo Alto water?
11.4 gpg, equal to 10.9 °dH, 19.5 °fH or 195 mg/L calcium carbonate.
What dishwasher salt setting should I use in Palo Alto?
For 195 mg/L (10.9 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Palo Alto?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: California SWRCB Division of Drinking Water, EDT lab results, system CA4310009 (2025-09). Method: own measurement. California SWRCB Division of Drinking Water, EDT lab results, system CA4310009 · Outdated figure? Tell us