Water hardness in Exeter
9.3 gpg hard
Tap water in Exeter is hard: 9.3 gpg (160 mg/L · 9 °dH · 16 °fH).
Source: City of Exeter 2025 Consumer Confidence Report (Table 3, Hardness row) (2022) · data checked 2026-11-04
Range across supply zones: 110–230 mg/L.
This figure is over 3 years old; hardness may have changed.
Exeter, California, is supplied by City of Exeter Public Works from groundwater wells. The figure of 160 mg/L as CaCO3 (hard) comes from a 2022 sample listed in the 2025 report, with a range of 110 to 230 mg/L, so it is dated and may differ today. Wells can vary between sources, so the hardness at your tap may sit anywhere in that range. A softener or descaling routine for the water heater is worth considering.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 9.3 gpg |
|---|---|
| Utility | City of Exeter Public Works (groundwater wells) |
How Exeter compares
- Tap water in Exeter is close to the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 664 of 1372 in the United States (1 = hardest); 51 % of these cities have softer water.
- In California it is number 171 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 Exeter
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 9 °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 Exeter water hard or soft?
It is hard: 160 mg/L as CaCO₃ (9.3 gpg, 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 Exeter 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 Exeter water?
9.3 gpg, equal to 9 °dH, 16 °fH or 160 mg/L calcium carbonate.
What dishwasher salt setting should I use in Exeter?
For 160 mg/L (9 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Exeter?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: City of Exeter 2025 Consumer Confidence Report (Table 3, Hardness row) (2022). Method: older figure, source currently unavailable. City of Exeter 2025 Consumer Confidence Report (Table 3, Hardness row) · Outdated figure? Tell us