Sodium in well water
The county where Sodium is found above the limit most often is Rockingham County, New Hampshire: 56% of 2,769 private wells tested, according to NH DHHS.
Sodium enters wells with road salt and from softeners. EPA's guidance level of 20 mg/L matters for people on sodium-restricted diets; most people are not affected below 250 mg/L.
- Health guideline
- 20 mg/L
- New Hampshire level
- 20 mg/L
- CAS number
- 7440-23-5
Where sodium is worst, by homeowner tests
Counties ranked by the share of private wells above the state guidance level in tests homeowners sent to the state lab. Shares combine town summaries, weighted by wells tested.
| County | Wells tested | Above state level | Highest | |
|---|---|---|---|---|
| Rockingham County, New Hampshire | 2,769 | 56% | 747 mg/L | |
| Strafford County, New Hampshire | 472 | 46% | 687 mg/L | |
| Hillsborough County, New Hampshire | 3,286 | 43% | 633 mg/L | |
| Belknap County, New Hampshire | 1,473 | 34% | 1,335 mg/L | |
| Merrimack County, New Hampshire | 4,194 | 32% | 2,186 mg/L | |
| Carroll County, New Hampshire | 1,627 | 29% | 699 mg/L | |
| Cheshire County, New Hampshire | 450 | 28% | 550 mg/L | |
| Grafton County, New Hampshire | 2,110 | 23% | 1,106 mg/L | |
| Sullivan County, New Hampshire | 607 | 21% | 478 mg/L | |
| Coos County, New Hampshire | 427 | 20% | 348 mg/L |
By individual samples
Counties with at least 30 individual samples in public monitoring data, against the EPA limit.
| County | Samples | Detected | Above EPA limit | Median |
|---|---|---|---|---|
| Rockingham County, New Hampshire | 328 | 99% | no limit | 16 mg/L |
| Cheshire County, New Hampshire | 67 | 97% | no limit | 8 mg/L |
| Carroll County, New Hampshire | 247 | 96% | no limit | 9 mg/L |
| Hillsborough County, New Hampshire | 260 | 96% | no limit | 12.3 mg/L |
| Strafford County, New Hampshire | 91 | 96% | no limit | 11 mg/L |
| Sullivan County, New Hampshire | 39 | 95% | no limit | 6.9 mg/L |
| Merrimack County, New Hampshire | 460 | 92% | no limit | 9 mg/L |
| Coos County, New Hampshire | 159 | 89% | no limit | 5.8 mg/L |
| Grafton County, New Hampshire | 214 | 88% | no limit | 7 mg/L |
| Belknap County, New Hampshire | 160 | 87% | no limit | 9 mg/L |
How to test
Use a state-certified lab and a proper sampling bottle; hardware-store strips cannot measure sodium at the levels that matter. Collect from the kitchen tap before any treatment, and again after treatment if you install it.
How to treat
- Point-of-use reverse osmosis
- Distillation