Well Water Nerd

Chloride in well water

1in5

private wells tested in Lewis County, Missouri had chloride above the limit, the highest share of any county, according to Missouri DHSS private well sampling summaries.

Chloride mainly comes from road salt and water softener discharge. Above 250 mg/L water tastes salty and corrodes plumbing. Rising chloride in a well usually means road salt is reaching the aquifer.

Nuisance level
250 mg/L
Missouri level
250 mg/L
CAS number
16887-00-6

Check your chloride 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 chloride

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 chloride

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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 chloride

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 chloride 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
Lewis County, Missouri116
Pike County, Missouri38
Henry County, Missouri62
Allegheny County, Pennsylvania39336 mg/L
Wyoming County, Pennsylvania571537 mg/L
Mercer County, Pennsylvania46479 mg/L
Ralls County, Missouri97
Lincoln County, Missouri104
Pike County, Pennsylvania711543 mg/L
Rockingham County, New Hampshire3,0202,490 mg/L
St. Charles County, Missouri60
Luzerne County, Pennsylvania413966 mg/L
Chester County, Pennsylvania47408 mg/L
Montgomery County, Pennsylvania53334 mg/L
Washington County, Pennsylvania164565 mg/L

By individual samples

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

CountyAbove EPA limitSamplesDetectedMedian
Caddo County, Louisianano limit871100%40 mg/L
Acadia County, Louisianano limit592100%43 mg/L
Avoyelles County, Louisianano limit829100%54 mg/L
Penobscot County, Maineno limit64100%6.1 mg/L
Hancock County, Maineno limit41100%4.43 mg/L
Somerset County, Maineno limit57100%4.21 mg/L
Kennebec County, Maineno limit44100%15.1 mg/L
Hudspeth County, Texasno limit126100%156 mg/L
Lee County, Texasno limit126100%59 mg/L
Shelby County, Texasno limit41100%23 mg/L
Jefferson County, Texasno limit128100%140 mg/L
Tyler County, Texasno limit72100%23.5 mg/L
Ellis County, Texasno limit55100%88 mg/L
Cumberland County, Maineno limit380100%29.1 mg/L
Concordia County, Louisianano limit240100%130 mg/L

How to test

Use a state-certified lab and a proper sampling bottle; hardware-store strips cannot measure chloride 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