Water Hardness in New Hampshire (NH)
New Hampshire has an average water hardness of 15 ppm (0.9 grains per gallon), which is classified as Soft . New Hampshire enjoys naturally soft water that requires no softening treatment. Residents benefit from easy soap lathering, spot-free dishes, and long-lasting plumbing and appliances. Water hardness varies between cities — from 10 ppm in Keene to 22 ppm in Portsmouth.
Water Hardness by City in New Hampshire
The table below shows water hardness data for 8 cities in New Hampshire, sorted from hardest to softest. Click any city name for detailed information including water source, treatment recommendations, and estimated hard water costs.
| City | Hardness (PPM) | Grains/Gallon | Level | Water Source | pH | TDS | Utility |
|---|---|---|---|---|---|---|---|
| Portsmouth | 22 ppm | 1.3 gpg | Soft | Ground | 7 | 35 | Portsmouth Water Division |
| Dover | 20 ppm | 1.2 gpg | Soft | Ground | 7 | 32 | City of Dover Public Works |
| Nashua | 18 ppm | 1.1 gpg | Soft | Mixed | 6.9 | 30 | Pennichuck Water Works |
| Rochester | 16 ppm | 0.9 gpg | Soft | Ground | 6.9 | 28 | City of Rochester Water Department |
| Concord | 14 ppm | 0.8 gpg | Soft | Surface | 6.8 | 24 | Concord Water Department |
| Manchester | 12 ppm | 0.7 gpg | Soft | Surface | 6.8 | 22 | Manchester Water Works |
| Lebanon | 12 ppm | 0.7 gpg | Soft | Surface | 6.8 | 20 | Lebanon Water Department |
| Keene | 10 ppm | 0.6 gpg | Soft | Surface | 6.7 | 18 | City of Keene |
Understanding Water Hardness in New Hampshire
Water Sources in New Hampshire
The majority of cities in New Hampshire draw their water from surface sources such as rivers, lakes, and reservoirs. Surface water generally contains fewer dissolved minerals than groundwater, which helps explain the overall hardness profile of the state. Cities that rely on surface water tend to have softer water because the water has less contact time with mineral-bearing rock formations underground.
Hardness Variation Across New Hampshire
Water hardness in New Hampshire ranges from 10 ppm in Keene to 22 ppm in Portsmouth — a difference of 12 ppm. This variation means that treatment recommendations differ significantly between cities. Even the hardest water in New Hampshire is moderate enough that a water softener is optional rather than essential, though homeowners who value spotless dishes and softer-feeling water may still find one worthwhile. Meanwhile, Keene enjoys naturally soft water that needs no treatment at all — an advantage that saves residents money on both equipment and ongoing maintenance.
How New Hampshire Compares to Other States
Below is a comparison of New Hampshire with five states that have similar average water hardness levels. Understanding how your state compares can help you gauge whether your water is typical for the region or unusually hard or soft.
| State | Avg Hardness | Level | Cities |
|---|---|---|---|
| New Hampshire (NH) | 15 ppm | Soft | 8 |
| Maine (ME) | 15 ppm | Soft | 7 |
| Massachusetts (MA) | 20 ppm | Soft | 8 |
| Vermont (VT) | 20 ppm | Soft | 8 |
| Washington (WA) | 25 ppm | Soft | 8 |
| Oregon (OR) | 30 ppm | Soft | 8 |
Find Your City's Water Hardness
Use our water hardness lookup tool to find your specific city in New Hampshire, or browse all 50 states to compare water hardness across the country. If your water is hard, visit our treatment solutions guide to find the right softener or conditioner for your home.