Water hardness in Dover
5 gpg moderately hard
Tap water in Dover is moderately hard: 5 gpg (86 mg/L · 4.8 °dH · 8.6 °fH).
Source: Delaware Drinking Water Watch, chemical sample results, system DE0000579 (2026-07) · data checked 2026-10-19
Range across supply zones: 23–120 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| Dover Air Force Base | 5.9 | 101 | moderately hard |
| Dover Water Department | 4.2 | 71 | moderately hard |
Two systems serve Dover in Delaware's Drinking Water Watch data. Dover Water Department reads a median of 71.1 mg/L as CaCO3 (4.2 gpg), with a range of 22.6 to 119.8 mg/L from 8 samples in 2026. The Dover Air Force Base system reads 100.5 mg/L (5.9 gpg) from 8 samples since 2019. The page shows the median of the two. Both are moderately hard or softer.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 5 gpg |
|---|---|
| Utility | Dover Air Force Base |
How Dover compares
- Tap water in Dover is 45 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1083 of 1372 in the United States (1 = hardest); 21 % of these cities have softer water.
- In Delaware it is number 1 of 3 cities; the regional median is 3.5 gpg.
- Nearest city with clearly softer water: Vineland, 56 km away (1.7 gpg).
- Nearest city with clearly harder water: Penns Grove, 63 km away (6.7 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Dover
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 5 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H1 |
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 Dover water hard or soft?
It is moderately hard: 86 mg/L as CaCO₃ (5 gpg, 4.8 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Dover 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 Dover water?
5 gpg, equal to 4.8 °dH, 8.6 °fH or 86 mg/L calcium carbonate.
What dishwasher salt setting should I use in Dover?
For 86 mg/L (4.8 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Dover?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Delaware Drinking Water Watch, chemical sample results, system DE0000579 (2026-07). Method: own measurement. Delaware Drinking Water Watch, chemical sample results, system DE0000579 · Outdated figure? Tell us