Water hardness in Los Gatos
8.8 gpg hard
Tap water in Los Gatos is hard: 8.8 gpg (151 mg/L · 8.5 °dH · 15.1 °fH).
Source: San Jose Water 2025 Annual Water Quality Report (CA4310011 main system) (2025) · data checked 2026-11-02
Range across supply zones: 77–451 mg/L.
3 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| Groundwater | 16.8 | 288 | very hard |
| Imported surface water | 5.8 | 99 | moderately hard |
| Mountain surface water | 8.8 | 151 | hard |
San Jose Water Company's 2025 report for its main system gives a median of 151 mg/L as CaCO3 across 3 zones, with a range of 77 to 451 mg/L. That is a very wide spread, so the hardness at your tap depends on which zone serves you. Check your zone before choosing a softener.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 8.8 gpg |
|---|---|
| Utility | San Jose Water Company |
How Los Gatos compares
- Tap water in Los Gatos is close to the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 703 of 1372 in the United States (1 = hardest); 49 % of these cities have softer water.
- In California it is number 185 of 336 cities; the regional median is 9.5 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 Los Gatos
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 8 °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 Los Gatos water hard or soft?
It is hard: 151 mg/L as CaCO₃ (8.8 gpg, 8.5 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Los Gatos 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 Los Gatos water?
8.8 gpg, equal to 8.5 °dH, 15.1 °fH or 151 mg/L calcium carbonate.
What dishwasher salt setting should I use in Los Gatos?
For 151 mg/L (8.5 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Los Gatos?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: San Jose Water 2025 Annual Water Quality Report (CA4310011 main system) (2025). Method: figure published by the water supplier. San Jose Water 2025 Annual Water Quality Report (CA4310011 main system) · Outdated figure? Tell us