Water hardness in Gardena
11.1 gpg very hard
Tap water in Gardena is very hard: 11.1 gpg (190 mg/L · 10.6 °dH · 19 °fH).
Source: Golden State Water Company 2025 Water Quality Report, Southwest System (2025) · data checked 2026-10-20
Range across supply zones: 137–280 mg/L.
Golden State Water Company's 2025 report for its Southwest System lists hardness of 137 to 280 mg/L (8.0 to 16.4 gpg). We show 190 mg/L, which is very hard. The range is wide, and we could not tell where your address falls in it, so your tap may be nearer either end. Scale on fixtures and heaters is likely, and a softener is worth considering.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 11.1 gpg |
|---|---|
| Utility | Golden State Water Company (Southwest System) |
How Gardena compares
- Tap water in Gardena is 23 % harder than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 561 of 1372 in the United States (1 = hardest); 58 % of these cities have softer water.
- In California it is number 135 of 336 cities; the regional median is 9.5 gpg.
- Nearest city with clearly softer water: Signal Hill, 16 km away (6.7 gpg).
- Nearest city with clearly harder water: Compton, 8 km away (15.8 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 Gardena
| Brand | Setting for this water |
|---|---|
| Bosch | H03 |
| Miele | 11 °dH |
| AEG / Electrolux | 2 |
| 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 Gardena water hard or soft?
It is very hard: 190 mg/L as CaCO₃ (11.1 gpg, 10.6 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Gardena 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 Gardena water?
11.1 gpg, equal to 10.6 °dH, 19 °fH or 190 mg/L calcium carbonate.
What dishwasher salt setting should I use in Gardena?
For 190 mg/L (10.6 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Gardena?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Golden State Water Company 2025 Water Quality Report, Southwest System (2025). Method: figure published by the water supplier. Golden State Water Company 2025 Water Quality Report, Southwest System · Outdated figure? Tell us