Well Water Nerd

Sodium in well water

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private wells tested in Rockingham County, New Hampshire had sodium above the limit, the highest share of any county, 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

Check your sodium number

Type the value from your lab report. It is compared to the EPA limit, the same way the full interpretation does it.

Test your own well for sodium

Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.

Order the Tap Score well water test kit, from $209Already tested? Upload the report

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Systems that remove sodium

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Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.

For sodium

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

Rather have it installed and sized for your well? Book a free in-home water test with a licensed local company.

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.

CountyAbove state levelWells testedHighest
Rockingham County, New Hampshire2,769747 mg/L
Strafford County, New Hampshire472687 mg/L
Hillsborough County, New Hampshire3,286633 mg/L
Sheboygan County, Wisconsin7168.3 mg/L
Douglas County, Wisconsin1221,022 mg/L
Calumet County, Wisconsin122547 mg/L
Fond du Lac County, Wisconsin122461 mg/L
Belknap County, New Hampshire1,4731,335 mg/L
Washington County, Wisconsin36259 mg/L
Merrimack County, New Hampshire4,1942,186 mg/L
Carroll County, New Hampshire1,627699 mg/L
Cheshire County, New Hampshire450550 mg/L
Dodge County, Wisconsin123183 mg/L
Grafton County, New Hampshire2,1101,106 mg/L
Jefferson County, Wisconsin746259 mg/L

By individual samples

Counties with at least 30 individual samples in public monitoring data, against the EPA limit.

CountyAbove EPA limitSamplesDetectedMedian
Aroostook County, Maineno limit60100%3.4 mg/L
Cumberland County, Maineno limit397100%18.1 mg/L
Jefferson County, Texasno limit187100%209 mg/L
Tyler County, Texasno limit71100%21 mg/L
Shelby County, Texasno limit46100%136 mg/L
Lee County, Texasno limit92100%97 mg/L
Hunterdon County, New Jerseyno limit245100%13.6 mg/L
Monmouth County, New Jerseyno limit398100%3.5 mg/L
Gloucester County, New Jerseyno limit1,026100%26 mg/L
Mercer County, New Jerseyno limit273100%12 mg/L
Burlington County, New Jerseyno limit914100%2.7 mg/L
Sussex County, New Jerseyno limit174100%17.5 mg/L
Union County, New Jerseyno limit62100%23 mg/L
Hudspeth County, Texasno limit107100%160 mg/L
Somerset County, Maineno limit62100%3.85 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