Water Hardness in New Hampshire
How to read the New Hampshire results
State pages are screening and comparison hubs. They summarize ZIP, city, and water-system patterns so you can find the local page that best matches your home or utility.
Use the source coverage below to judge how much local confirmation a specific city or ZIP needs. The methodology page explains the source hierarchy, weighting, and limitations.
Data Source Coverage
ZIP-level source mix for New Hampshire; higher direct and USGS coverage means less reliance on regional estimates.
In New Hampshire, 33% of ZIPs use verified treated-water records, 46% use high-confidence USGS monitoring, and 22% use estimates that should be confirmed locally for treatment decisions.
What the Data Shows in New Hampshire
Most classified ZIPs in New Hampshire are below the hard-water threshold, though local systems can still vary.
New Hampshire uses a mixed data profile across treated-water records, USGS monitoring, and estimated fallback values.
Use the city table below to compare local results. For estimated locations or unusually high readings, confirm with your utility or a home hardness test before sizing treatment equipment.
ZIP Hardness Distribution
Treatment Takeaway
Hardness treatment is less likely to be needed statewide, but local water systems can still differ from the state pattern. Test first if you see scale or spotting.
How to Use This Data
The source coverage is relatively strong in New Hampshire, so these pages are useful for comparing local patterns before confirming your home's exact hardness.
Useful New Hampshire City Pages
Shortcuts to city pages backed by more ZIP-code or water-system data.
Cities With More Local Data
Prioritize cities with multiple ZIPs and systems, then use the local source badges to compare high-confidence USGS readings against estimated areas.
Top 10 Hardest Water Cities
| # | City | Hardness |
|---|---|---|
| 1 | Grantham | Moderately Hard (129 PPM) |
| 2 | Meriden | Moderately Hard (129 PPM) |
| 3 | Plainfield | Moderately Hard (129 PPM) |
| 4 | Newington | Slightly Hard (110 PPM) |
| 5 | Newmarket | Slightly Hard (109 PPM) |
| 6 | Brentwood | Slightly Hard (109 PPM) |
| 7 | Rye | Slightly Hard (108 PPM) |
| 8 | Epping | Slightly Hard (108 PPM) |
| 9 | Atkinson | Slightly Hard (107 PPM) |
| 10 | Stratham | Slightly Hard (107 PPM) |
All Cities in New Hampshire
City pages marked Estimated use fallback values and should be confirmed with local testing or utility data.