Hardness
Very Hard
255 PPM · 14.9 GPG
Local water dashboard
Official source aggregationWater quality in St. Louis, MO 63108
A source-transparent look at local hardness, associated public water systems, EPA compliance history, and the measurements that are—and are not—available for St. Louis City County.
No active health-based violation reported
- Primary matched system
- St Louis City Pws
- Source water
- Surface water
- County
- St. Louis City County
- Profile updated
At a glance
What the current records say
EPA quarter 2026Q2
Compliance screen
No active flag
0 active health-based records
Lead 90th percentile
0.0018 mg/L
12% of action level
Utility match
1 system
Serves 304,709 people system-wide
Hardness meter
How hard is the water?
Estimated local hardness
USGS hardness classification scale
255 PPM
Soft
0–59Moderate
60–120Hard
121–180Very hard
181+
0–59Moderate
60–120Hard
121–180Very hard
181+
Parts per million
255
mg/L as CaCO₃ equivalent
Grains per gallon
14.9
1 GPG ≈ 17.1 PPM
What this means at home
At 255 PPM, mineral scale can build up on fixtures and heating elements, reduce soap lather, and leave visible spotting. Hardness is primarily an aesthetic and appliance concern—not itself a tap-water safety rating.
USGS sites used
22
Nearest site
15.3 mi
Observation range
Jan 6, 2016–Jun 9, 2026
Estimate confidence
Moderate
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: Meramec River at Paulina Hills, MO (Stream).USGS source documentation ↗
Regional context
Is 63108 typical?
These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.
St. Louis median
255 PPM
About the same19 indexed ZIP readings · Range 254–256 PPM
Missouri median
236 PPM
19 PPM higher556 indexed ZIP readings · Range 38.3–483 PPM
EPA benchmark screen
Contaminant snapshot
Available numerical results from associated SDWIS community water systems, compared with the applicable action level or federal MCL. Federal measured-value coverage is incomplete.
1 pass
Lead (PB90)
0.0018 mg/L
Reported Dec 31, 2025
Copper (CU90)
Not available
No numerical 90th-percentile result
Numerical coverage
1 comparable result
Missing values remain blank; absence is not treated as a pass.
Lead (90th percentile)
Measured in mg/L
Local 0.0018
EPA limit 0.015
Share of EPA benchmark
100% line = listed limit
2026Q2
- All records
- 8
- Health-based
- 0
- Active health-based
- 0
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| Lead and Copper Rule | MO6010715 | Unaddressed | Dec 30, 2025 |
| LEAD AND COPPER RULE REVISIONS | MO6010715 | Unaddressed | Jul 2, 2025 |
| Simazine | MO6010715 | Resolved | Oct 1, 2022through Dec 31, 2022 |
| Atrazine | MO6010715 | Resolved | Oct 1, 2022through Dec 31, 2022 |
| LASSO | MO6010715 | Resolved | Oct 1, 2022through Dec 31, 2022 |
| Atrazine | MO6010715 | Resolved | Jul 1, 2022through Sep 30, 2022 |
| LASSO | MO6010715 | Resolved | Jul 1, 2022through Sep 30, 2022 |
| Simazine | MO6010715 | Resolved | Jul 1, 2022through Sep 30, 2022 |
No reported violation does not prove that every contaminant was tested or absent; SDWIS measured values are incomplete and lag state records.
Solutions matcher
Your personalized water action plan
Matched to St. Louis ZIP 63108 using 255 PPM nearby hardness and 1 reported measurement benchmarks.
Scale protection
High-Capacity Whole House Water Softener
255 PPM is 2× the high-hardness trigger used by this matcher.
Designed to reduce scale on fixtures, water heaters, glassware, and plumbing throughout the home.
Compare whole-house systemsAffiliate disclosure: we may earn a commission from qualifying purchases, at no added cost to you. Product matching is educational and does not replace certified water testing.
Nearby indexed reports
Compare ZIPs in St. Louis
Estimates can differ across a city because monitoring locations and associated systems differ.
Frequently asked
Water questions for St. Louis
Is tap water safe in St. Louis?+
EPA ECHO shows no active health-based violation for the associated systems in this reporting snapshot. This does not prove every contaminant is absent; federal records can lag and household plumbing can change tap conditions.
How hard is the water?+
Nearby USGS observations produce an estimate of 255 PPM, or 14.9 grains per gallon, classified as very hard. This is not a household tap measurement.
Do I need a water softener?+
At 255 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.