Water Hardness in Connecticut
Across 111 measured cities, Connecticut's median tap water hardness is 52.6 mg/L (3.1 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.
Connecticut 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 | 90 | 81.1% |
| Moderately hard | 60-120 mg/L | 16 | 14.4% |
| Hard | 120-180 mg/L | 5 | 4.5% |
| Very hard | >180 mg/L | 0 | 0.0% |
Hardest and Softest Water in Connecticut
Measured values only; labeled county estimates and values under active dispute never rank.
Hardest water in Connecticut
- Bristol — 162.0 mg/L (9.5 gpg), hard
- New Britain — 162.0 mg/L (9.5 gpg), hard
- Plantsville — 132.0 mg/L (7.7 gpg), hard
- Southington — 132.0 mg/L (7.7 gpg), hard
- Manchester — 131.0 mg/L (7.7 gpg), hard
Softest water in Connecticut
- Northwest Harwinton — 9.4 mg/L (0.6 gpg), soft
- Torrington — 9.4 mg/L (0.6 gpg), soft
- Blue Hills — 15.9 mg/L (0.9 gpg), soft
- East Hartford — 15.9 mg/L (0.9 gpg), soft
- Glastonbury Center — 15.9 mg/L (0.9 gpg), soft
Every Covered City in Connecticut
All 111 covered Connecticut 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 |
|---|---|---|---|---|
| Derby | 49.0 | 2.9 | Soft | Utility-reported |
| Newington | 15.9 | 0.9 | Soft | Utility-reported |
| Ansonia | 46.0 | 2.7 | Soft | Utility-reported |
| Orange | 46.0 | 2.7 | Soft | Utility-reported |
| Branford Center | 46.0 | 2.7 | Soft | Utility-reported |
| Cheshire Village | 46.0 | 2.7 | Soft | Utility-reported |
| East Haven | 46.0 | 2.7 | Soft | Utility-reported |
| Milford | 46.0 | 2.7 | Soft | Utility-reported |
| New Haven | 46.0 | 2.7 | Soft | Utility-reported |
| North Haven | 46.0 | 2.7 | Soft | Utility-reported |
| Northford | 46.0 | 2.7 | Soft | Utility-reported |
| Quinnipiac University | 46.0 | 2.7 | Soft | Utility-reported |
| West Haven | 46.0 | 2.7 | Soft | Utility-reported |
| Woodmont | 46.0 | 2.7 | Soft | Utility-reported |
| Wethersfield | 15.9 | 0.9 | Soft | Utility-reported |
| East Hartford | 15.9 | 0.9 | Soft | Utility-reported |
| Blue Hills | 15.9 | 0.9 | Soft | Utility-reported |
| Glastonbury Center | 15.9 | 0.9 | Soft | Utility-reported |
| Hartford | 15.9 | 0.9 | Soft | Utility-reported |
| West Hartford | 15.9 | 0.9 | Soft | Utility-reported |
| Long Hill | 50.2 | 2.9 | Soft | Utility-reported |
| Shelton | 52.1 | 3.0 | Soft | Utility-reported |
| Newtown | 52.6 | 3.1 | Soft | Utility-reported |
| Stamford | 52.6 | 3.1 | Soft | Utility-reported |
| Tashua | 52.6 | 3.1 | Soft | Utility-reported |
| Bridgeport | 52.6 | 3.1 | Soft | Utility-reported |
| Byram | 52.6 | 3.1 | Soft | Utility-reported |
| Coleytown | 52.6 | 3.1 | Soft | Utility-reported |
| Compo | 52.6 | 3.1 | Soft | Utility-reported |
| Cos Cob | 52.6 | 3.1 | Soft | Utility-reported |
| Daniels Farm | 52.6 | 3.1 | Soft | Utility-reported |
| Darien Downtown | 52.6 | 3.1 | Soft | Utility-reported |
| East Village | 52.6 | 3.1 | Soft | Utility-reported |
| Fairfield University | 52.6 | 3.1 | Soft | Utility-reported |
| Georgetown | 52.6 | 3.1 | Soft | Utility-reported |
| Glenville | 52.6 | 3.1 | Soft | Utility-reported |
| Greens Farms | 52.6 | 3.1 | Soft | Utility-reported |
| Greenwich | 52.6 | 3.1 | Soft | Utility-reported |
| Indian Field | 52.6 | 3.1 | Soft | Utility-reported |
| Lordship | 52.6 | 3.1 | Soft | Utility-reported |
| Mill Plain | 52.6 | 3.1 | Soft | Utility-reported |
| Murray | 52.6 | 3.1 | Soft | Utility-reported |
| New Canaan | 52.6 | 3.1 | Soft | Utility-reported |
| Noroton | 52.6 | 3.1 | Soft | Utility-reported |
| Noroton Heights | 52.6 | 3.1 | Soft | Utility-reported |
| Norwalk | 52.6 | 3.1 | Soft | Utility-reported |
| Old Greenwich | 52.6 | 3.1 | Soft | Utility-reported |
| Old Hill | 52.6 | 3.1 | Soft | Utility-reported |
| Oronoque | 52.6 | 3.1 | Soft | Utility-reported |
| Pemberwick | 52.6 | 3.1 | Soft | Utility-reported |
| Plattsville | 52.6 | 3.1 | Soft | Utility-reported |
| Poplar Plains | 52.6 | 3.1 | Soft | Utility-reported |
| Ridgefield | 52.6 | 3.1 | Soft | Utility-reported |
| Riverside | 52.6 | 3.1 | Soft | Utility-reported |
| Rock Ridge | 52.6 | 3.1 | Soft | Utility-reported |
| Route 7 Gateway | 52.6 | 3.1 | Soft | Utility-reported |
| Sacred Heart University | 52.6 | 3.1 | Soft | Utility-reported |
| Sandy Hook | 52.6 | 3.1 | Soft | Utility-reported |
| Saugatuck | 52.6 | 3.1 | Soft | Utility-reported |
| South Wilton | 52.6 | 3.1 | Soft | Utility-reported |
| Southport | 52.6 | 3.1 | Soft | Utility-reported |
| Staples | 52.6 | 3.1 | Soft | Utility-reported |
| Stepney | 52.6 | 3.1 | Soft | Utility-reported |
| Stratford Downtown | 52.6 | 3.1 | Soft | Utility-reported |
| Tokeneke | 52.6 | 3.1 | Soft | Utility-reported |
| Trumbull Center | 52.6 | 3.1 | Soft | Utility-reported |
| West Mountain | 52.6 | 3.1 | Soft | Utility-reported |
| Westport Village | 52.6 | 3.1 | Soft | Utility-reported |
| Wilton Center | 52.6 | 3.1 | Soft | Utility-reported |
| Bristol | 162.0 | 9.5 | Hard | Utility-reported |
| Waterbury | 66.0 | 3.9 | Moderately hard | Utility-reported |
| Hazardville | 110.8 | 6.5 | Moderately hard | Utility-reported |
| Southwood Acres | 110.8 | 6.5 | Moderately hard | Utility-reported |
| New Britain | 162.0 | 9.5 | Hard | Utility-reported |
| Broad Brook | 61.3 | 3.6 | Moderately hard | Utility-reported |
| Rockville | 61.3 | 3.6 | Moderately hard | Utility-reported |
| Sherwood Manor | 61.3 | 3.6 | Moderately hard | Utility-reported |
| Somers | 61.3 | 3.6 | Moderately hard | Utility-reported |
| Suffield Depot | 61.3 | 3.6 | Moderately hard | Utility-reported |
| Thompsonville | 61.3 | 3.6 | Moderately hard | Utility-reported |
| Windsor Locks | 61.3 | 3.6 | Moderately hard | Utility-reported |
| Bethel | 83.1 | 4.9 | Moderately hard | Utility-reported |
| Danbury | 83.1 | 4.9 | Moderately hard | Utility-reported |
| Ridgebury | 83.1 | 4.9 | Moderately hard | Utility-reported |
| Clinton | 48.1 | 2.8 | Soft | Utility-reported |
| Manchester | 131.0 | 7.7 | Hard | Utility-reported |
| Stonington | 36.5 | 2.1 | Soft | Utility-reported |
| New London | 21.0 | 1.2 | Soft | Utility-reported |
| Waterford | 21.0 | 1.2 | Soft | Utility-reported |
| Middletown | 64.1 | 3.8 | Moderately hard | Utility-reported |
| Plantsville | 132.0 | 7.7 | Hard | Utility-reported |
| Southington | 132.0 | 7.7 | Hard | Utility-reported |
| Northwest Harwinton | 9.4 | 0.6 | Soft | Utility-reported |
| Torrington | 9.4 | 0.6 | Soft | Utility-reported |
| Fenwick | 54.7 | 3.2 | Soft | Utility-reported |
| Guilford Center | 54.7 | 3.2 | Soft | Utility-reported |
| Madison Center | 54.7 | 3.2 | Soft | Utility-reported |
| Old Saybrook Center | 54.7 | 3.2 | Soft | Utility-reported |
| Saybrook Manor | 54.7 | 3.2 | Soft | Utility-reported |
| Westbrook Center | 54.7 | 3.2 | Soft | Utility-reported |
| Conning Towers-Nautilus Park | 22.5 | 1.3 | Soft | Utility-reported |
| Groton | 22.5 | 1.3 | Soft | Utility-reported |
| Groton Long Point | 22.5 | 1.3 | Soft | Utility-reported |
| Noank | 22.5 | 1.3 | Soft | Utility-reported |
| Poquonock Bridge | 22.5 | 1.3 | Soft | Utility-reported |
| Storrs | 96.6 | 5.7 | Moderately hard | Computed from Ca+Mg |
| Naugatuck | 66.0 | 3.9 | Moderately hard | Utility-reported |
| Oxoboxo River | 23.4 | 1.4 | Soft | Utility-reported |
| Mystic | 22.7 | 1.3 | Soft | Utility-reported |
| Old Mystic | 22.7 | 1.3 | Soft | Utility-reported |
| Gales Ferry | 23.4 | 1.4 | Soft | Utility-reported |
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 Connecticut's Water Hardness
Connecticut sits in the New England crystalline uplands region.
New England sits on granite, gneiss, and schist - crystalline bedrock with almost no carbonate minerals for water to dissolve. Ample rain and snowmelt move quickly through thin, glacially scoured soils into rivers and upland reservoirs without picking up much calcium or magnesium. That is why the USGS maps this region among the softest water in the country.
Connecticut Water Hardness FAQ
Does Connecticut have hard water?
On the whole, no — Connecticut's statewide median sits below the hard threshold, though some cities run harder. The median is 52.6 mg/L (3.1 gpg) — soft on the USGS scale, where anything above 120 mg/L (7 gpg) counts as hard. 5 of Connecticut's 111 measured cities fall in the hard or very hard bands (5%), so check your own city rather than the state average.
How hard is tap water in Connecticut?
Across the 111 Connecticut cities with measured values in our index, the median hardness is 52.6 mg/L (3.1 gpg) — soft on the USGS scale. Individual cities range from 9.4 to 162.0 mg/L, so check your own city rather than assuming the state number.
Which city in Connecticut has the hardest water?
Bristol has the hardest measured tap water in our Connecticut index at 162.0 mg/L (9.5 gpg) — hard 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 Connecticut?
5 of Connecticut's 111 measured cities (5%) 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 Connecticut 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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