Hardness
Hard
137 PPM · 8 GPG
Local water dashboard
Official source aggregationWater quality in Inola, OK 74036
A source-transparent look at local hardness, associated public water systems, EPA compliance history, and the measurements that are—and are not—available for Rogers County.
1 reported benchmark flag
- Primary matched system
- Inola Water Works Inc
- Source water
- Surface water
- County
- Rogers 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 mg/L
0% of action level
Utility match
1 system
Serves 1,589 people system-wide
Hardness meter
How hard is the water?
Estimated local hardness
USGS hardness classification scale
137 PPM
Soft
0–59Moderate
60–120Hard
121–180Very hard
181+
0–59Moderate
60–120Hard
121–180Very hard
181+
Parts per million
137
mg/L as CaCO₃ equivalent
Grains per gallon
8
1 GPG ≈ 17.1 PPM
What this means at home
At 137 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
11
Nearest site
54.4 mi
Observation range
Jan 26, 2016–Apr 20, 2026
Estimate confidence
Low
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: Illinois River South of Siloam Springs, AR (Stream).USGS source documentation ↗
Regional context
Is 74036 typical?
These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.
Inola median
137 PPM
About the same1 indexed ZIP readings · Range 137–137 PPM
Oklahoma median
226 PPM
89 PPM lower148 indexed ZIP readings · Range 7–610 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 pass1 fail
Lead (PB90)
0 mg/L
Reported Dec 31, 2023
Copper (CU90)
Not available
No numerical 90th-percentile result
Numerical coverage
2 comparable results
Missing values remain blank; absence is not treated as a pass.
Lead (90th percentile)
Measured in mg/L
Local 0
EPA limit 0.015
TTHM
Measured in MG/L
Local 0.082
EPA limit 0.08
Share of EPA benchmark
100% line = listed limit
2026Q2
- All records
- 8
- Health-based
- 3
- Active health-based
- 0
| Contaminant or rule | System | Status | Period |
|---|---|---|---|
| TTHM | OK3006612 | Unaddressed | Dec 30, 2025 |
| TTHMHealth-basedReported 0.082 MG/L · MCL 0.08 | OK3006612 | Archived | Jul 1, 2025through Sep 30, 2025 |
| TTHMHealth-basedReported 0.085 MG/L · MCL 0.08 | OK3006612 | Archived | Jul 1, 2025through Sep 30, 2025 |
| TTHM | OK3006612 | Resolved | Apr 1, 2025through Jun 12, 2025 |
| LEAD AND COPPER RULE REVISIONS | OK3006612 | Resolved | Oct 17, 2024through Jul 15, 2025 |
| LEAD AND COPPER RULE REVISIONSHealth-based | OK3006612 | Resolved | Oct 17, 2024through Jul 15, 2025 |
| Chlorine | OK3006612 | Resolved | Sep 1, 2024through Sep 30, 2024 |
| Revised Total Coliform Rule | OK3006612 | Resolved | Sep 1, 2024through Sep 30, 2024 |
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 Inola ZIP 74036 using 137 PPM nearby hardness and 2 reported measurement benchmarks.
Scale protection
High-Capacity Whole House Water Softener
137 PPM is 1× 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 systemsDrinking water protection
Under-Sink Reverse Osmosis System
TTHM has a measured benchmark flag or active health-based SDWIS record in this profile.
A certified multi-stage RO system targets a broader range of dissolved contaminants at the kitchen tap.
Explore under-sink filtrationAffiliate 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.
Frequently asked
Water questions for Inola
Is tap water safe in Inola?+
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 137 PPM, or 8 grains per gallon, classified as hard. This is not a household tap measurement.
Do I need a water softener?+
At 137 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.