Hardness
Very Hard
317.5 PPM · 18.6 GPG
Local water dashboard
Official source aggregationWater quality in Cottage Grove, MN 55016
A source-transparent look at local hardness, associated public water systems, EPA compliance history, and the measurements that are—and are not—available for Washington County.
No active health-based violation reported
- Primary matched system
- Cottage Grove
- Source water
- Groundwater
- County
- Washington 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
0.002 mg/L
13% of action level
Utility match
1 system
Serves 42,760 people system-wide
Hardness meter
How hard is the water?
Estimated local hardness
USGS hardness classification scale
317.5 PPM
Soft
0–59Moderate
60–120Hard
121–180Very hard
181+
0–59Moderate
60–120Hard
121–180Very hard
181+
Parts per million
317.5
mg/L as CaCO₃ equivalent
Grains per gallon
18.6
1 GPG ≈ 17.1 PPM
What this means at home
At 317.5 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
88
Nearest site
4.4 mi
Observation range
Jul 11, 2016–Aug 30, 2018
Estimate confidence
Moderate
Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: PDCJ-U11 028N21W27CDABDD01 W815 0000427865 (Well).USGS source documentation ↗
Regional context
Is 55016 typical?
These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.
Cottage Grove median
318 PPM
About the same1 indexed ZIP readings · Range 317.5–317.5 PPM
Minnesota median
318 PPM
About the same319 indexed ZIP readings · Range 46.1–716 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)
0.002 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 0.002
EPA limit 0.015
Share of EPA benchmark
100% line = listed limit
2026Q2
- All records
- 0
- Health-based
- 0
- Active health-based
- 0
No violation record was returned for the associated systems in the imported lookback window beginning Jan 1, 2021.
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 Cottage Grove ZIP 55016 using 317.5 PPM nearby hardness and 1 reported measurement benchmarks.
Scale protection
High-Capacity Whole House Water Softener
317.5 PPM is 3× 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.
Frequently asked
Water questions for Cottage Grove
Is tap water safe in Cottage Grove?+
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 317.5 PPM, or 18.6 grains per gallon, classified as very hard. This is not a household tap measurement.
Do I need a water softener?+
At 317.5 PPM, a correctly sized whole-house softener can reduce scale and hard-water spotting. It does not replace contaminant filtration.