Cumberland County, Illinois: Private Well Water Arsenic Risk
USGS models estimate the private-well arsenic exposure across Cumberland County. The arsenic figure is an area estimate; the measurements are of other wells — neither is a test of your own well.
Quick answer: Arsenic is the headline concern for Cumberland County well water: USGS modeling estimates about 140 residents on private wells with arsenic above the EPA limit of 10 µg/L. These figures describe wells across the Illinois county — not your tap — so the only way to know your own water is a certified lab test.
This is a modeled probability for the area, not a measurement of your well. USGS statistical models estimate how many private wells in this area are likely to exceed the federal limit — they cannot tell you what is in your water. Two neighbors can have very different results. The only way to know your well is to test it.
~140
people estimated to rely on private wells with modeled arsenic above the 10 µg/L EPA limit
111–176
90% confidence range for that estimate
10 µg/L
EPA maximum contaminant level for arsenic
Find out what's actually in your well
USGS models flag arsenic in Cumberland County, but two wells on the same road can test very differently. Arsenic, nitrate and coliform bacteria are the three most common private-well problems, and none of them has a taste or smell. A certified lab test checks all of them at once; the CDC and EPA recommend testing every well at least once a year.
Basic screening only. Confirm arsenic, nitrate and bacteria with a certified lab.
Find a certified drinking-water labAmazon links are affiliate links — we may earn a commission at no extra cost to you.
Measured well tests in Cumberland County
Not enough USGS well samples in Cumberland County (fewer than 5 wells for any parameter). See the Illinois state page for counties with measured nitrate, manganese, iron and pH.
Arsenic in Cumberland County drinking water: what the estimate means
Arsenic occurs naturally in bedrock and can dissolve into groundwater, so it shows up in private wells with no color, taste or smell. The USGS estimate above combines a statistical model of arsenic probability with the number of people on domestic wells in Cumberland County. A higher number means more of your neighbors are likely drinking water over the federal limit — but your own well could be higher or lower. Long-term arsenic exposure is linked to skin, bladder and lung cancers, so the EPA sets the limit at 10 µg/L.
Because arsenic is tasteless and invisible, a certified lab test is the only way to detect it — and unlike bacteria, boiling does not remove arsenic (it slightly concentrates it as water evaporates). A lab reports total arsenic; if yours is elevated, reverse osmosis or an adsorptive arsenic filter reduces it, while carbon pitchers and water softeners do not.
What to do
- Test your well for arsenic, nitrate — it's the only way to know your actual level.
- If arsenic or nitrate is present, install a reverse-osmosis system — carbon pitchers do not remove either.
- Re-test annually; well chemistry changes over time.
Cumberland County well water: frequently asked questions
Is there arsenic in Cumberland County drinking water?
Arsenic occurs naturally in the bedrock under Cumberland County, Illinois, and dissolves into some private wells with no color, taste or smell. USGS modeling estimates about 140 residents (range 111–176) on private wells with arsenic above the EPA limit of 10 µg/L. These are area and other-well figures, not a test of your own well — the only way to know your arsenic level is a certified lab test of your tap.
How do I remove arsenic from Cumberland County well water?
Test first so you know your level and form of arsenic. If arsenic is present, a point-of-use reverse-osmosis system under the kitchen sink removes 90%+ of it; carbon pitchers and standard "filter" jugs do not remove arsenic or nitrate. Whole-house treatment (adsorptive arsenic media) is used when the level is high. Re-test after installing and then annually.
Match the filter to your test result
Carbon pitchers and faucet filters do not remove arsenic or nitrate. Reverse osmosis is the point-of-use fix; a whole-house system handles the rest of the home.
APEC ROES-50 5-Stage Reverse Osmosis System
5-stage RO, ★ 4.7 — removes arsenic, nitrate, lead, fluoride and PFAS.
Check price on Amazon →Whole-house well water system
Treats every tap, shower and appliance — the right scale for sediment, iron, sulfur and bacteria on a private well.
Compare on Amazon →Waterdrop arsenic-reduction filters
Under-sink units tested for arsenic reduction — the point-of-use fix for a well over the limit.
Shop on Waterdrop direct →Affiliate links — we may earn a commission at no extra cost to you. Re-test after installing to confirm the system is working.