Water hardness in Wilmington (Delaware)
3.5 gpg moderately hard
Tap water in Wilmington (Delaware) is moderately hard: 3.5 gpg (61 mg/L · 3.4 °dH · 6 °fH).
Source: Delaware Drinking Water Watch, chemical sample results, system DE0000663 (2021-05) · data checked 2026-10-19
Range across supply zones: 58–67 mg/L.
This figure is over 3 years old; hardness may have changed.
The Wilmington, Delaware figure comes from Delaware's Drinking Water Watch portal for the Wilmington Water Department. It rests on 8 samples, all taken in 2021: a median of 60.5 mg/L as CaCO3 (3.5 gpg), with a range of 58.4 to 67.1 mg/L. The data is older. The water sits at the soft to moderately hard line, and scale is mild.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 3.5 gpg |
|---|---|
| Utility | Wilmington Water Department |
How Wilmington (Delaware) compares
- Tap water in Wilmington (Delaware) is 61 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1177 of 1372 in the United States (1 = hardest); 14 % of these cities have softer water.
- In Delaware it is number 2 of 3 cities; the regional median is 3.5 gpg.
- Nearest city with clearly softer water: Vineland, 55 km away (1.7 gpg).
- Nearest city with clearly harder water: Penns Grove, 5 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 Wilmington
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 3 °dH |
| AEG / Electrolux | 1 |
| Beko | 1st |
| Hoover | S0 |
| LG | H0 |
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 Wilmington (Delaware) water hard or soft?
It is moderately hard: 61 mg/L as CaCO₃ (3.5 gpg, 3.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Wilmington (Delaware) 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 Wilmington (Delaware) water?
3.5 gpg, equal to 3.4 °dH, 6 °fH or 61 mg/L calcium carbonate.
What dishwasher salt setting should I use in Wilmington (Delaware)?
For 61 mg/L (3.4 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Wilmington (Delaware)?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Delaware Drinking Water Watch, chemical sample results, system DE0000663 (2021-05). Method: own measurement. Delaware Drinking Water Watch, chemical sample results, system DE0000663 · Outdated figure? Tell us