Slidell, LA water hardness

Tap water hardness
42mg/L
2.5gpg
SoftCounty estimate

County estimate from 2,987 water samples in St. Tammany Parish · July 2026

LA typical
102 mg/L
EPA health violations since 2016
1
Data
County estimate

Water samples from around Slidell put hardness at about 42 mg/L (2.5 gpg), which would be soft on the USGS scale. Treat this as a rough guide: it is the median of 2,987 samples taken across St. Tammany Parish, mostly wells and streams, not a test of Slidell's treated tap water.

Slidell on the hardness scale, with nearby cities
060120180240300360+LA typical 102Covington: 4 mg/LCovington 4Mandeville: 48 mg/LMandeville 48Metairie: 135 mg/LMetairie 135New Orleans: 153 mg/LNew Orleans 153Gretna: 153 mg/LGretna 153Belle Chasse: 153 mg/LBelle Chasse 153Jefferson: 154 mg/LJefferson 154Bridge City: 154 mg/LBridge City 154Elmwood: 154 mg/LElmwood 154Marrero: 154 mg/LMarrero 154Slidell 42mg/L as calcium carbonate060120180240300360+LA 102Covington: 4 mg/LCovington 4Mandeville: 48 mg/LMandeville 48Metairie: 135 mg/LMetairie 135New Orleans: 153 mg/LNew Orleans 153Gretna: 153 mg/LGretna 153Jefferson: 154 mg/LJefferson 15442 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Slidell sits 60 mg/L below the typical Louisiana figure of 102. Of the 10 nearest cities we track, 1 has softer water and 9 have harder. The range nearby runs from 4 mg/L in Covington to 154 in Jefferson.

What 42 mg/L means at home

Soap and shampoo lather with very little product. Kettles and showerheads stay mostly free of white crust.

Some people notice that soap feels slow to rinse off in soft water. That slippery feel is normal and harmless.

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

Nothing, as far as hardness goes. At 42 mg/L a softener would have almost nothing to remove.

Carbon filter

If the water tastes of chlorine, a pitcher or faucet carbon filter takes care of that. It does not change hardness.

EPA record for Slidell's water system

City of Slidell Water Supply · PWSID LA1103041

1 health-based violation since 2016

Serves about 35,547 people from groundwater.

Health-based
1
Monitoring or reporting
0
Open now
0

EPA lists this system as serving Slidell.

20162017201820192020202120222023202420252026Total Coliform Rule'16'18'20'22'24'26Total Coliform Rule
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Total Coliform Rulebacteria12022Resolved

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 Slidell water hard?

No. It measures about 42 mg/L (2.5 grains per gallon), which the USGS classes as soft.

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

About 2.5 gpg. One grain per gallon equals 17.1 mg/L, so 42 mg/L divided by 17.1 gives 2.5.

Has the Slidell water system had EPA violations?

EPA records show 1 health-based violation for City of Slidell Water Supply since 2016, involving Total Coliform Rule.

Nearby cities

All 32 cities in Louisiana

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.