The flagship Michigan well problem
Arsenic removal for Michigan well water
If arsenic showed up on your Michigan well test, the fix is established and local contractors install it routinely: reverse osmosis or adsorption media at the tap, or a point-of-entry system when the situation calls for one. The federal limit is 10 ug/L with a health goal of zero, per the EPA arsenic rule, and the right equipment depends on your number, your water chemistry, and where you want the treated water. We connect you with an independent licensed contractor who works from your lab report, free.
No lab result yet? Read Your Michigan Well Test, Explained and start with a certified test. Treatment gets sized from a number, not a worry.
Why do Michigan wells have arsenic at all?
Geology, not pollution. The Marshall Sandstone aquifer under the Thumb and Southeast Michigan carries arsenic-rich pyrite, with bulk intervals measured up to 1,020 ppm arsenic, documented by Kolker and others, 2003 (USGS). Wells drawing from that bedrock, or from glacial deposits derived from it, are the ones more likely to test high. That makes arsenic a probability-by-aquifer question: your county and your well's source layer set the odds, and only a test settles them.
What the nine-county USGS study found
A USGS and MDEQ study of arsenic records from 3,022 domestic and public wells across nine Southeast Michigan and Thumb counties (Genesee, Huron, Lapeer, Livingston, Oakland, Sanilac, Shiawassee, Tuscola, and Washtenaw) found county median arsenic spanning this range, per USGS:
| County median | Arsenic | Against the 10 ug/L limit |
|---|---|---|
| Washtenaw County, the lowest of the nine | 2.9 ug/L | Under the limit |
| Genesee County, the highest of the nine | 16.6 ug/L | Over the limit |
A median over the federal limit means more than half the sampled Genesee wells were over it. The remaining seven counties fell between these two, and every county in the study had some wells above 10 ug/L. County-level detail lives on the Genesee, Lapeer, and Huron county pages.
The arsenite problem: why equipment choice matters here
Arsenic in water comes in two forms, and Michigan drew the harder one. In a study of 73 Southeast Michigan wells, 53 to 98 percent of dissolved arsenic was arsenite, As(III), the more mobile form that treatment has to target specifically, with concentrations ranging from 0.5 to 278 ug/L and a mean near 29 ug/L (Kim, Nriagu, and Haack 2002, Environmental Pollution).
The practical consequence: adsorption media and reverse osmosis membranes are generally better at catching the other form, arsenate. Water heavy in arsenite often needs an oxidation step ahead of the main equipment so the arsenic converts to the form the system is designed to reduce. This is exactly the kind of sizing decision that belongs to a contractor holding your actual lab report, and it is why two houses with the same arsenic number can end up with different, equally correct systems.
Point of use or point of entry: which one do I need?
For arsenic alone, point of use usually wins. EGLE's arsenic in well water guidance names point-of-use reverse osmosis and arsenic adsorption cartridges as the most effective and practical residential treatment, because drinking and cooking water is the exposure that matters. Point of entry earns its keep when arsenic arrives with company.
Point of use (POU): the kitchen-tap fix
A reverse osmosis unit under the sink, certified under NSF/ANSI standard 58, or an adsorption cartridge, treats the water you actually swallow. Smaller equipment, lower cost, and the fit for most arsenic-only results.
Point of entry (POE): the whole-house fix
Adsorption media or oxidation-plus-filtration where the water line enters the house. The usual reason: your report also shows iron, manganese, or hardness, and one planned whole-house system handles the set in the right order.
A useful side note from EPA treatment practice: when raw water carries a lot of iron, oxidation and filtration of that iron also carries arsenic down with it. Contractors use this, which is one more reason the iron line on your report changes the arsenic plan. If iron is your bigger number, start at the iron and manganese page.
How the free match works for arsenic
Step one
Send your numbers
County, water source, and your arsenic result if you have one. If you have not tested, testing options in Michigan come first, and we say so.
Step two
Meet the contractor
An independent licensed professional who handles arsenic work in your county reviews the report, checks the water chemistry, and quotes POU, POE, or both, in writing.
Step three
Verify, then decide
Check the credentials below, compare the quote against the numbers it was sized from, and hire or walk away. The match costs nothing either way.
Check the credentials yourself
Verify your water treatment contractor
You never have to take anyone's word for their credentials, including anyone this site matches you with. Michigan keeps public records for the people and independent listings for the equipment. Four places to look before you sign:
EGLE contractor registration
Michigan registers water well drilling contractors and pump installation contractors through EGLE under Part 127 of the Public Health Code, renewed every year. If a project touches your well or its pump, ask for the registration number and check it with EGLE.
EGLE water well contractor registrationNSF-certified equipment
Certification to an NSF/ANSI standard means an independent lab verified the claim on the label: NSF/ANSI 44 for cation-exchange softeners, 53 for named health contaminants, 58 for reverse osmosis systems. Ask which standard a proposed unit carries, then look the model up in NSF listings.
NSF standards for water treatment systemsYour county health department
County health departments issue well permits, keep well records, and run private well sampling programs. They are the local authority on your well, and MDHHS publishes statewide guidance for well owners. Neither works for any contractor, which is exactly why their answers are useful.
MDHHS well water guidanceEGLE-certified drinking water labs
EGLE certifies the drinking water laboratories whose results Michigan health departments accept. Any treatment quote should be sized from a certified lab report, and EGLE recommends testing for coliform bacteria and nitrate every year.
How to get your water tested, EGLEThree questions worth asking any water treatment contractor
- 1. Are you registered with EGLE for any well or pump work this project involves, and what is the registration number?
- 2. Which NSF/ANSI standard is this equipment certified to, and for which specific contaminant claims?
- 3. Will you size the system from a certified lab result, and will the written quote list the water numbers it was designed around?
Matching through this site is not an endorsement, and these checks work on anyone. A good contractor answers all three without hesitation.
Arsenic treatment questions
How likely is arsenic in my Michigan well?
It depends on your aquifer, not on a statewide average. Homes drawing from the Marshall Sandstone under the Thumb and Southeast Michigan are more likely to test high, and in a nine-county USGS study, county medians ran from 2.9 ug/L in Washtenaw to 16.6 ug/L in Genesee. Two neighboring wells can still differ, so the only real answer is a certified lab test.
Does boiling water remove arsenic?
No. Boiling concentrates arsenic as water evaporates, so the number goes up, not down. Standard carbon pitcher filters are not designed for it either. The technology classes designed to reduce arsenic are reverse osmosis, certified under NSF/ANSI standard 58, and arsenic adsorption media, with oxidation ahead of them when the water chemistry calls for it.
Do I treat the whole house or just the kitchen tap?
For arsenic alone, EGLE guidance points to a point-of-use unit at the drinking and cooking tap as the practical residential fix, because ingestion is the exposure that matters. Whole-house arsenic treatment exists and makes sense in some situations, usually when iron or other findings are being treated at the point of entry anyway.
Who installs the arsenic treatment system?
An independent licensed local contractor. Great Lakes Well Water is a free matching service run by a marketing company: we connect you with a professional who works your county, and that contractor tests, sizes, quotes in writing, and installs. Your agreement is directly with them, and this page explains what to verify before you sign.