Hard water in Duncanville, TX
County estimate from 2,497 water samples in Dallas County · July 2026
- TX typical
- 112 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- County estimate
Water samples from around Duncanville put hardness at about 164 mg/L (9.6 gpg), which would be hard on the USGS scale. Treat this as a rough guide: it is the median of 2,497 samples taken across Dallas County, mostly wells and streams, not a test of Duncanville's treated tap water. One more reason for caution: EPA lists Duncanville's water system as using surface water, which is often softer than the wells behind the county figure.
Duncanville sits 52 mg/L above the typical Texas figure of 112. None of the 10 nearest cities we track has harder water. The range nearby runs from 7 mg/L in Glenn Heights to 138 in Grand Prairie.
What 164 mg/L means at home
Expect white crust on faucets and showerheads, plus spots on dishes that come out of the dishwasher.
Kettles collect scale quickly. Water heaters build up sediment at the bottom of the tank, which makes them work harder over time.
Soap and detergent need a little more to lather, and soap scum shows up in the tub.
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
At 164 mg/L most of the trouble is scale, and only a few things deal with it.
Ion-exchange water softener
The standard whole-house fix. It swaps calcium and magnesium for sodium or potassium and needs salt plus a drain. Size it with the calculator below.
Salt-free conditioner
No salt and no drain line. It changes how minerals form scale instead of removing them, so water still tests hard.
Reverse osmosis or carbon filter
Under-sink reverse osmosis removes minerals from drinking water only. Plain carbon filters improve taste but do not soften.
3 people × 75 gallons a day × 9.6 gpg = 2,158 grains a day. A 24,000-grain unit regenerates about every 11 days.
EPA record for Duncanville's water system
No health-based violations since 2016
Serves about 39,413 people from surface water.
- Health-based
- 0
- Monitoring or reporting
- 1
- Open now
- 0
EPA lists this system as serving Duncanville.
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 Duncanville water hard?
Yes. It measures about 164 mg/L (9.6 grains per gallon), which the USGS classes as hard.
What is the water hardness in Duncanville in grains per gallon?
About 9.6 gpg. One grain per gallon equals 17.1 mg/L, so 164 mg/L divided by 17.1 gives 9.6.
What size water softener do I need in Duncanville?
For 3 people using 75 gallons each per day, 9.6 gpg works out to about 2,158 grains a day. A 24,000-grain softener covers that with a regeneration about every 11 days.
Has the Duncanville water system had EPA violations?
EPA records show no health-based violations for City of Duncanville since 2016. There were also 1 monitoring or reporting violation, which are about late or missing tests and notices.
Nearby cities
- DeSoto126 mg/LHard
- Cedar Hill16 mg/LSoft
- Grand Prairie138 mg/LHard
- Glenn Heights7 mg/LSoft
- Lancaster96 mg/LModerately hard
- Red Oak86 mg/LModerately hard
- Arlington91 mg/LModerately hard
- Midlothian41 mg/LSoft
- Mansfield53 mg/LSoft
- Dallas112 mg/LModerately hard
Hardness data: TapWaterData US Water Hardness (county estimate, July 4, 2026), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.