Water hardness in Poway
13.6 gpg very hard
Tap water in Poway is very hard: 13.6 gpg (233 mg/L · 13 °dH · 23.3 °fH).
Source: City of Poway Annual Water Quality Report 2021 (2021) · data checked 2026-11-02
Range across supply zones: 207–273 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| Imported water | 15.1 | 258 | very hard |
| Lake Poway water (treated at Berglund WTP) | 12.1 | 207 | very hard |
This figure is over 3 years old; hardness may have changed.
The City of Poway's 2021 water quality report gives a median of 232.5 mg/L across two zones, ranging from 207 to 273 mg/L. That is very hard water. Expect visible limescale on fixtures and appliances, and consider a softener or scale-control device for water heaters.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 13.6 gpg |
|---|---|
| Utility | City of Poway Utilities |
How Poway compares
- Tap water in Poway is 50 % harder than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 419 of 1372 in the United States (1 = hardest); 70 % of these cities have softer water.
- In California it is number 87 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
- 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 Poway
| Brand | Setting for this water |
|---|---|
| Bosch | H04 |
| Miele | 13 °dH |
| AEG / Electrolux | 3 |
| Beko | 4th |
| 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 Poway water hard or soft?
It is very hard: 233 mg/L as CaCO₃ (13.6 gpg, 13 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Poway 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 Poway water?
13.6 gpg, equal to 13 °dH, 23.3 °fH or 233 mg/L calcium carbonate.
What dishwasher salt setting should I use in Poway?
For 233 mg/L (13 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Poway?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: City of Poway Annual Water Quality Report 2021 (2021). Method: figure published by the water supplier. City of Poway Annual Water Quality Report 2021 · Outdated figure? Tell us