Water Hardness in Delaware
Across 42 measured cities — with 15 more covered by labeled county-level estimates — Delaware's median tap water hardness is 40.1 mg/L (2.3 gpg): soft on the USGS scale. Below: every covered city, the state's hardest and softest water, and the geology that explains it.
Data updated July 6, 2026. Sources: utility-reported water quality data and USGS/EPA Water Quality Portal samples.
Delaware Cities by Hardness Category
Measured cities only — labeled county estimates never enter the category counts or the median.
| Category | Range | Measured cities | Share |
|---|---|---|---|
| Soft | 0-60 mg/L | 23 | 54.8% |
| Moderately hard | 60-120 mg/L | 19 | 45.2% |
| Hard | 120-180 mg/L | 0 | 0.0% |
| Very hard | >180 mg/L | 0 | 0.0% |
Hardest and Softest Water in Delaware
Measured values only; labeled county estimates and values under active dispute never rank.
Hardest water in Delaware
- Middletown — 51.5 mg/L (3.0 gpg), soft
- Dover — 39.5 mg/L (2.3 gpg), soft
- Kent Acres — 39.5 mg/L (2.3 gpg), soft
- Rodney Village — 39.5 mg/L (2.3 gpg), soft
- Clayton — 34.6 mg/L (2.0 gpg), soft
Softest water in Delaware
- Milton — 7.2 mg/L (0.4 gpg), soft
- Selbyville — 8.2 mg/L (0.5 gpg), soft
- Long Neck — 9.8 mg/L (0.6 gpg), soft
- Dagsboro — 10.7 mg/L (0.6 gpg), soft
- Georgetown — 10.7 mg/L (0.6 gpg), soft
Every Covered City in Delaware
All 57 covered Delaware cities, sorted by population served. "County estimate" rows are labeled context values from USGS/EPA Water Quality Portal county sampling — they never enter the median above. City names link to each city's full water quality page.
| City | Hardness (mg/L) | gpg | Category | Data |
|---|---|---|---|---|
| Wilmington | 87.4 | 5.1 | Moderately hard | Utility-reported |
| New Castle | 87.4 | 5.1 | Moderately hard | Utility-reported |
| Wilmington Manor | 87.4 | 5.1 | Moderately hard | Utility-reported |
| Elsmere | 87.4 | 5.1 | Moderately hard | Utility-reported |
| Hockessin | 87.4 | 5.1 | Moderately hard | Utility-reported |
| Brookside | 87.4 | 5.1 | Moderately hard | Utility-reported |
| Edgemoor | 87.4 | 5.1 | Moderately hard | Utility-reported |
| Greenville | 87.4 | 5.1 | Moderately hard | Utility-reported |
| Newport | 87.4 | 5.1 | Moderately hard | Utility-reported |
| North Star | 87.4 | 5.1 | Moderately hard | Utility-reported |
| Pike Creek | 87.4 | 5.1 | Moderately hard | Utility-reported |
| Pike Creek Valley | 87.4 | 5.1 | Moderately hard | Utility-reported |
| Glasgow | 90.4 | 5.3 | Moderately hard | Utility-reported |
| Newark | 94.3 | 5.5 | Moderately hard | Utility-reported |
| Bear | 94.3 | 5.5 | Moderately hard | Utility-reported |
| Delaware City | 94.3 | 5.5 | Moderately hard | Utility-reported |
| St. Georges | 94.3 | 5.5 | Moderately hard | Utility-reported |
| Dover | 39.5 | 2.3 | Soft | Utility-reported |
| Kent Acres | 39.5 | 2.3 | Soft | Utility-reported |
| Rodney Village | 39.5 | 2.3 | Soft | Utility-reported |
| Bellefonte | 71.5 | 4.2 | Moderately hard | Utility-reported |
| Highland Acres | 32.0 | 1.9 | Soft | Utility-reported |
| Bethany Beach | 34.2 | 2.0 | Soft | Utility-reported |
| Camden | 16.3 | 0.9 | Soft | Utility-reported |
| Dover Base Housing | 16.3 | 0.9 | Soft | Utility-reported |
| Little Creek | 16.3 | 0.9 | Soft | Utility-reported |
| Rising Sun-Lebanon | 16.3 | 0.9 | Soft | Utility-reported |
| Wyoming | 16.3 | 0.9 | Soft | Utility-reported |
| Ocean View | 34.0 | 2.0 | Soft | Utility-reported |
| Millville | 34.0 | 2.0 | Soft | Utility-reported |
| South Bethany | 34.2 | 2.0 | Soft | Utility-reported |
| Smyrna | 31.2 | 1.8 | Soft | Utility-reported |
| Clayton | 34.6 | 2.0 | Soft | Utility-reported |
| Lewes | 40.8 | 2.4 | Soft | Utility-reported |
| Long Neck | 9.8 | 0.6 | Soft | Utility-reported |
| Middletown | 51.5 | 3.0 | Soft | Utility-reported |
| Fenwick Island | 50.1 | 2.9 | Soft | County estimate |
| Odessa | 71.7 | 4.2 | Moderately hard | Utility-reported |
| Milton | 7.2 | 0.4 | Soft | Utility-reported |
| Milford | 50.1 | 2.9 | Soft | County estimate |
| Harrington | 64.9 | 3.8 | Moderately hard | County estimate |
| Selbyville | 8.2 | 0.5 | Soft | Utility-reported |
| Bridgeville | 50.1 | 2.9 | Soft | County estimate |
| Cheswold | 64.9 | 3.8 | Moderately hard | County estimate |
| Dagsboro | 10.7 | 0.6 | Soft | Utility-reported |
| Felton | 64.9 | 3.8 | Moderately hard | County estimate |
| Frederica | 64.9 | 3.8 | Moderately hard | County estimate |
| Winterthur | 109.0 | 6.4 | Moderately hard | County estimate |
| Lincoln | 50.1 | 2.9 | Soft | County estimate |
| Laurel | 50.1 | 2.9 | Soft | County estimate |
| Georgetown | 10.7 | 0.6 | Soft | Utility-reported |
| Kenton | 29.2 | 1.7 | Soft | Utility-reported |
| Ellendale | 50.1 | 2.9 | Soft | County estimate |
| Frankford | 50.1 | 2.9 | Soft | County estimate |
| Townsend | 109.0 | 6.4 | Moderately hard | County estimate |
| Millsboro | 50.1 | 2.9 | Soft | County estimate |
| Delmar | 50.1 | 2.9 | Soft | County estimate |
Above 120 mg/L (7 gpg), scale is usually worth treating — see our water softener guide, or size a system with the hardness calculator & converter.
The Geology Behind Delaware's Water Hardness
Delaware sits in the Appalachian and Mid-Atlantic mixed terrain region.
The Mid-Atlantic and Appalachian states sit on a patchwork of sandstone, shale, and crystalline rock that yields mostly soft to moderately hard water. The big exception is the region's limestone and dolomite valleys - including the carbonate belt running from Pennsylvania down through the Shenandoah Valley - where groundwater dissolves calcium and magnesium readily and comes out distinctly hard. A city's number here depends heavily on whether its supply draws from upland rivers and reservoirs or from carbonate-valley wells.
Delaware Water Hardness FAQ
Does Delaware have hard water?
On the whole, no — Delaware's statewide median sits below the hard threshold, though some cities run harder. The median is 40.1 mg/L (2.3 gpg) — soft on the USGS scale, where anything above 120 mg/L (7 gpg) counts as hard. 0 of Delaware's 42 measured cities fall in the hard or very hard bands (0%), so check your own city rather than the state average.
How hard is tap water in Delaware?
Across the 42 Delaware cities with measured values in our index, the median hardness is 40.1 mg/L (2.3 gpg) — soft on the USGS scale. Individual cities range from 7.2 to 94.3 mg/L, so check your own city rather than assuming the state number.
Which city in Delaware has the hardest water?
Middletown has the hardest measured tap water in our Delaware index at 51.5 mg/L (3.0 gpg) — soft on the USGS scale. Rankings use measured utility values only; labeled county estimates and values under active dispute are excluded.
Do I need a water softener in Delaware?
0 of Delaware's 42 measured cities (0%) fall in the hard or very hard bands — above 120 mg/L (7 gpg), the level where most water treatment professionals suggest considering an ion-exchange softener. Hardness varies utility to utility, so look up your own city's value before sizing equipment.
How do I find my city's exact water hardness?
Enter your ZIP code in our free lookup at tapwaterdata.com/zip to see the value we hold for your Delaware city from utility-reported water quality data, check your water utility's annual Consumer Confidence Report (CCR), or use a home test-strip kit.
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