How hard is the water in Danbury, CT?

Tap water hardness
83mg/L
4.9gpg
Moderately hard

Reported by Danbury Water Department · June 2025

CT typical
53 mg/L
EPA health violations since 2016
1
Softener for 3 people
24k grain
Data
Utility report

Danbury water measures 83 mg/L (4.9 gpg) of hardness, moderately hard by USGS standards. The number comes from Danbury Water Department, dated June 2025.

Danbury on the hardness scale, with nearby cities
060120180240300360+CT typical 53Long Hill: 50 mg/LLong Hill 50Shelton: 52 mg/LShelton 52Ridgefield: 53 mg/LRidgefield 53Sandy Hook: 53 mg/LSandy Hook 53Daniels Farm: 53 mg/LDaniels Farm 53New Canaan: 53 mg/LNew Canaan 53Staples: 53 mg/LStaples 53Trumbull Center: 53 mg/LTrumbull Center 53Bridgeport: 53 mg/LBridgeport 53Bethel: 83 mg/LBethel 83Danbury 83mg/L as calcium carbonate060120180240300360+CT 53Long Hill: 50 mg/LLong Hill 50Ridgefield: 53 mg/LRidgefield 53Sandy Hook: 53 mg/LSandy Hook 53Daniels Farm: 53 mg/LDaniels Fa. 53New Canaan: 53 mg/LNew Canaan 53Bethel: 83 mg/LBethel 8383 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

At 83 mg/L, Danbury is 30 mg/L above the typical Connecticut figure of 53. None of the 10 nearest cities we track has harder water. The range nearby runs from 50 mg/L in Long Hill to 83 in Bethel.

What 83 mg/L means at home

You may see faint white spots on glasses and shower doors after the water dries.

Scale builds up slowly. A kettle or coffee maker needs descaling now and then, maybe every few months.

Hardness is not a health problem, and EPA sets no limit for it. It is a matter of scale and soap.

What to do about it

Optional. Plenty of households at this level live with it and descale the kettle now and then.

Water softener

Worth a look if spots on glass bother you, or if your tankless water heater manual asks for softer water.

Carbon filter

Improves taste and removes chlorine. It leaves calcium and magnesium in place.

Softener size for Danbury

3 people × 75 gallons a day × 4.9 gpg = 1,094 grains a day. A 24,000-grain unit regenerates about every 21 days.

Size it for your household

EPA record for Danbury's water system

Danbury Water Department · PWSID CT0340011

1 health-based violation since 2016

Serves about 62,055 people from surface water.

Health-based
1
Monitoring or reporting
9
Open now
0
20162017201820192020202120222023202420252026Surface Water Treatment Rule'16'18'20'22'24'26Surface Water Treatment Rule
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Surface Water Treatment Rulefiltration and disinfection12021Resolved

Health-based means a contaminant above its legal limit or a missed treatment step. Monitoring and reporting violations are late or missing tests and notices. Source: EPA ECHO, 2026Q3 export, violations with periods starting 2016 or later. Full EPA record.

Questions

Is Danbury water hard?

Somewhat. It measures about 83 mg/L (4.9 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Danbury in grains per gallon?

About 4.9 gpg. One grain per gallon equals 17.1 mg/L, so 83 mg/L divided by 17.1 gives 4.9.

What size water softener do I need in Danbury?

For 3 people using 75 gallons each per day, 4.9 gpg works out to about 1,094 grains a day. A 24,000-grain softener covers that with a regeneration about every 21 days.

Has the Danbury water system had EPA violations?

EPA records show 1 health-based violation for Danbury Water Department since 2016, involving Surface Water Treatment Rule. There were also 9 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 51 cities in Connecticut

Hardness data: TapWaterData US Water Hardness (utility report, June 9, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.