Water hardness in Norwalk (California)
17.6 gpg very hard
Tap water in Norwalk (California) is very hard: 17.6 gpg (302 mg/L · 16.9 °dH · 30.1 °fH).
Source: California SWRCB Division of Drinking Water, EDT lab results, system CA1910191 (2025-07) · data checked 2026-10-19
Range across supply zones: 120–482 mg/L.
The Norwalk figure comes from State Water Resources Control Board lab results for the city's own water department, which serves only part of Norwalk. It rests on 4 well results from 2022 to 2025: a median of 301.5 mg/L as CaCO3 (17.6 gpg), with a range of 120 to 482 mg/L. The sample is small and the range is wide. The water is very hard on median.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 17.6 gpg |
|---|---|
| Utility | Norwalk - City, Water Dept. |
How Norwalk (California) compares
- Tap water in Norwalk (California) is 94 % harder than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 246 of 1372 in the United States (1 = hardest); 82 % of these cities have softer water.
- In California it is number 46 of 336 cities; the regional median is 9.5 gpg.
- Nearest city with clearly softer water: Artesia, 4 km away (8.6 gpg).
- Nearest city with clearly harder water: Monterey Park, 16 km away (22.2 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 Norwalk
| Brand | Setting for this water |
|---|---|
| Bosch | H05 |
| Miele | 17 °dH |
| AEG / Electrolux | 4 |
| Beko | 5th |
| Hoover | S3 |
| LG | H3 |
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 Norwalk (California) water hard or soft?
It is very hard: 302 mg/L as CaCO₃ (17.6 gpg, 16.9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Norwalk (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 Norwalk (California) water?
17.6 gpg, equal to 16.9 °dH, 30.1 °fH or 302 mg/L calcium carbonate.
What dishwasher salt setting should I use in Norwalk (California)?
For 302 mg/L (16.9 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Norwalk (California)?
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 CA1910191 (2025-07). Method: own measurement. California SWRCB Division of Drinking Water, EDT lab results, system CA1910191 · Outdated figure? Tell us