Water Hardness in Delaware
Across 12 measured cities — with 25 more covered by labeled county-level estimates — Delaware's median tap water hardness is 37.7 mg/L (2.2 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 September 13, 2026. Sources: utility-reported water quality data and USGS/EPA Water Quality Portal samples.
What it costs to soften Delaware water
Water softener cost in Delaware at 2.2 gpg prices the equipment and the installation labour against the plumber wages published for Delaware, and labels every range as modelled or measured rather than leaving you to guess which it is.
Delaware · 2.2 grains per gallon
$955–$1,235
installed, midpoint $1,079 — a 24,000-grain unit, the size 4 people at this hardness need.
Salt and drain water over 10 years: $440–$1,033 — the 2,409,000 grains of hardness this household removes, at the national salt price and water rate whose sources are named below. Filter changes and Service contract are omitted rather than assumed.
Sized for 4 people regenerating every 7 days: 4,620 grains of capacity needed, rounded up to the next common residential size. The median of 12 measured Delaware cities in our hardness dataset. Modelled: the standard build band published for that state at the size this hardness calls for, equipment priced 2026-10-04 against the May 2025 reference period (OEWS M2025). Salt: the median retailer price of 3 retailers, read 2026-10-04, at a declared salt dose per regeneration. Drain water: about 50 gallons per regeneration from a government extension estimate read 2026-10-04, at the 2024 national average water and sewer rate from a government source read 2026-10-04.
Deciding whether it is worth it at all? Start from how much a water softener costs nationally — the same equipment, installation and ten-year ownership breakdown before any state wage adjustment is applied.
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 | 8 | 66.7% |
| Moderately hard | 60-120 mg/L | 4 | 33.3% |
| 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
- Dover — 55.7 mg/L (3.3 gpg), soft
- Lewes — 41.2 mg/L (2.4 gpg), soft
- Smyrna — 27.4 mg/L (1.6 gpg), soft
- Long Neck — 9.8 mg/L (0.6 gpg), soft
- Selbyville — 8.2 mg/L (0.5 gpg), soft
Softest water in Delaware
- Selbyville — 8.2 mg/L (0.5 gpg), soft
- Long Neck — 9.8 mg/L (0.6 gpg), soft
- Smyrna — 27.4 mg/L (1.6 gpg), soft
- Lewes — 41.2 mg/L (2.4 gpg), soft
- Dover — 55.7 mg/L (3.3 gpg), soft
Every Covered City in Delaware
All 37 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 |
|---|---|---|---|---|
| Bear | 94.3 | 5.5 | Moderately hard | Utility-reported |
| Hockessin | 94.3 | 5.5 | Moderately hard | Utility-reported |
| Wilmington | 109.0 | 6.4 | Moderately hard | County estimate |
| New Castle | 71.5 | 4.2 | Moderately hard | Utility-reported |
| Newark | 109.0 | 6.4 | Moderately hard | County estimate |
| Dover | 55.7 | 3.3 | Soft | Utility-reported |
| Millville | 34.2 | 2.0 | Soft | Utility-reported |
| Middletown | 109.0 | 6.4 | Moderately hard | County estimate |
| Bethany Beach | 50.1 | 2.9 | Soft | County estimate |
| Smyrna | 27.4 | 1.6 | Soft | Utility-reported |
| Long Neck | 9.8 | 0.6 | Soft | Utility-reported |
| Fenwick Island | 50.1 | 2.9 | Soft | County estimate |
| Lewes | 41.2 | 2.4 | Soft | Utility-reported |
| Georgetown | 50.1 | 2.9 | Soft | County estimate |
| Clayton | 64.9 | 3.8 | Moderately hard | County estimate |
| Odessa | 71.7 | 4.2 | Moderately hard | 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 |
| Milton | 50.1 | 2.9 | Soft | County estimate |
| Bridgeville | 50.1 | 2.9 | Soft | County estimate |
| Cheswold | 64.9 | 3.8 | Moderately hard | County estimate |
| Ocean View | 30.1 | 1.8 | Soft | Utility-reported |
| Felton | 64.9 | 3.8 | Moderately hard | County estimate |
| Delaware City | 109.0 | 6.4 | Moderately hard | County estimate |
| Dagsboro | 50.1 | 2.9 | Soft | 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 |
| 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 |
| St. Georges | 109.0 | 6.4 | Moderately hard | 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 37.7 mg/L (2.2 gpg) — soft on the USGS scale, where anything above 120 mg/L (7 gpg) counts as hard. 0 of Delaware's 12 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 12 Delaware cities with measured values in our index, the median hardness is 37.7 mg/L (2.2 gpg) — soft on the USGS scale. Individual cities range from 8.2 to 94.3 mg/L, so check your own city rather than assuming the state number.
Which city in Delaware has the hardest water?
Dover has the hardest measured tap water in our Delaware index at 55.7 mg/L (3.3 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 12 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.
Need whole-house or professional water treatment?
For the problems a pitcher or under-sink filter cannot fix — scale, rust and black staining, sulfur smell, well contamination, or test results you cannot explain. Tell us what is happening and we will connect you with a local water-treatment professional.
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