Water hardness in Tucson
13.4 gpg very hard
Tap water in Tucson is very hard: 13.4 gpg (229 mg/L · 12.8 °dH · 22.9 °fH).
Source: Tucson Water, Water Quality in Your Neighborhood dashboard (latest quarterly results) (2026-01) · data checked 2026-10-22
Range across supply zones: 78–340 mg/L.
Tucson Water relies on groundwater and on Colorado River water delivered by the Central Arizona Project, which is recharged into basins in Avra Valley and south of the city and then pumped back out. The blend varies by area, hence the range of 78.3–340 mg/L around 229 mg/L CaCO₃. Hard water here leaves scale on evaporative coolers, fixtures and water heaters.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 13.4 gpg |
|---|---|
| Utility | Tucson Water |
How Tucson compares
- Tap water in Tucson is 48 % harder than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 437 of 1372 in the United States (1 = hardest); 68 % of these cities have softer water.
- In Arizona it is number 6 of 12 cities; the regional median is 13 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 Tucson
| 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 Tucson water hard or soft?
It is very hard: 229 mg/L as CaCO₃ (13.4 gpg, 12.8 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Tucson 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 Tucson water?
13.4 gpg, equal to 12.8 °dH, 22.9 °fH or 229 mg/L calcium carbonate.
What dishwasher salt setting should I use in Tucson?
For 229 mg/L (12.8 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Tucson?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Tucson Water, Water Quality in Your Neighborhood dashboard (latest quarterly results) (2026-01). Method: computed from supplier's calcium and magnesium. Tucson Water, Water Quality in Your Neighborhood dashboard (latest quarterly results) · Outdated figure? Tell us