The result-in-hand guide
Your Michigan well test, explained
A lab report from a Michigan well is a short table of numbers with no instructions. This page is the instructions. Find each line of your report below, see which band your number lands in, read what that band means in plain language, and see which class of treatment equipment addresses it, with every figure cited to the agency that set it.
The bands here cover the findings that dominate Michigan well reports: arsenic in the Thumb and Southeast Michigan, iron, manganese, and hardness almost everywhere, nitrate in farm country, coliform bacteria anywhere, and PFAS near documented plume sites. About 1.12 million Michigan households draw from a private well, per MDHHS, and the state leaves those wells in the owner's hands. The report you are holding is how you run yours.
No result yet? Start with free and low-cost well testing in Michigan and come back with numbers.
How do I read a well water report?
Match each row of your report to a limit: the result column shows what the lab measured, and the limit column shows the standard it is compared against. Two kinds of standards appear. Health-based limits, like the federal arsenic and nitrate maximums, mark levels the EPA regulates in public water supplies. Aesthetic guidelines, like the iron and manganese secondary standards, mark where water starts staining, tasting, or smelling wrong without being a health-based violation. Private wells are not required to meet either, which is the point of this page: the number is yours to act on, and the bands below tell you when acting makes sense.
Arsenic: what does my number mean?
The federal limit for arsenic is 10 ug/L, and the EPA health goal is zero, per the EPA arsenic rule. At or above 10, treat the drinking water. Below 10, treatment is a personal call that gets stronger as the number climbs toward the limit, because the health goal sits at zero.
-
Below 10 ug/L
Under the federal limit. No action is required. Because the EPA health goal is zero, some households with mid-single-digit results still add a drinking-water unit at the kitchen tap. Retest on your normal schedule, and retest sooner after well work.
-
10 ug/L or higher
Over the federal limit. EGLE's arsenic in well water guidance names point-of-use reverse osmosis and arsenic adsorption cartridges as the most effective and practical residential fixes. Genesee County's median in a nine-county USGS study was 16.6 ug/L, so results like this are a known, solvable Michigan situation, not a rarity.
Michigan arsenic is geological. It comes from arsenic-rich pyrite in the Marshall Sandstone aquifer under the Thumb and Southeast Michigan, documented by Kolker and others, 2003 (USGS), so homes drawing from that aquifer are more likely to test high. Much of it also arrives as arsenite, a form treatment has to target specifically, which is why the equipment choice belongs to someone working from your actual number.
Get matched for arsenic treatmentIron and manganese: why is my water staining everything?
Iron above 0.3 mg/L and manganese above 0.05 mg/L explain orange stains, black residue, and metallic taste. Those are the EPA secondary standards, set for nuisance effects rather than health, and they are the most commonly crossed lines on Michigan well reports.
-
Iron at or below 0.3 mg/L, manganese at or below 0.05 mg/L
Within the secondary standards. Staining and taste problems are unlikely to come from these two lines, so if fixtures are still orange, look at other rows of the report or at the plumbing.
-
Iron above 0.3 mg/L or manganese above 0.05 mg/L
Expect stains, residue, and taste, and expect them to worsen as the numbers rise. The standard fixes are oxidizing filters, air injection systems, and greensand-type media that convert dissolved metals to particles and filter them out, sized to the measured levels and your household's flow.
Nitrate: is 10 mg/L really the line?
Yes. The federal limit is 10 mg/L for nitrate as nitrogen, with 1 mg/L for nitrite, per the EPA National Primary Drinking Water Regulations. Nitrate matters most for infants and during pregnancy, so a result near the line deserves a prompt retest rather than a wait.
-
Below 10 mg/L
Under the limit. Results above natural background in a farming area are worth watching annually, because nitrate levels move with the seasons and with what happens upfield of your well.
-
10 mg/L or higher
Over the limit. Talk to your county health department, especially with an infant or a pregnancy in the house, and plan treatment. Reverse osmosis and anion exchange are the technology classes designed to reduce nitrate at the tap or for the household.
Nitrate concentrates in Michigan's agricultural counties, and boiling makes it worse, not better, by concentrating what is in the pot. This is one line where the fix is strictly treatment or a different source.
Get matched for nitrate treatmentHardness: what counts as hard water in Michigan?
The USGS classification calls water hard at 121 mg/L of calcium carbonate, about seven grains per gallon, and very hard above 180 mg/L. Most Michigan groundwater lands in the hard-to-very-hard bands, which is why softeners are close to standard equipment on wells here.
| Band | mg/L as calcium carbonate | Grains per gallon |
|---|---|---|
| Soft | 0 to 60 | 0 to 3.5 |
| Moderately hard | 61 to 120 | 3.6 to 7.0 |
| Hard | 121 to 180 | 7.1 to 10.5 |
| Very hard | Above 180 | Above 10.5 |
One grain per gallon equals about 17.1 mg/L, per USGS.
Hardness is a wallet problem, not a health problem: scale shortens water heater life, clogs fixtures, and dulls laundry. The standard fix is a cation-exchange softener, the technology class covered by NSF/ANSI standard 44, sized from your measured grains and household use rather than from a brochure.
Get matched for water softeningColiform bacteria: what does present mean?
Coliform results read present or absent rather than as a number. A present result means surface water or soil has a path into your well, and the finding to take most seriously is E. coli, which points to fecal contamination. Your county health department is the first call, and EGLE recommends this test every year.
-
Absent
The well showed no indicator bacteria on that sample day. Keep the annual test on the calendar, per EGLE's private well testing guidance, because one clean sample is a snapshot, not a warranty on the well.
-
Total coliform present
Something is reaching the aquifer or the well bore. The usual sequence: resample to rule out sampling error, inspect the well cap, casing, and grading, disinfect, then retest. A repeat hit means the well itself deserves a professional look.
-
E. coli present
Treat this result as your health department directs, use another water source for drinking in the meantime, and get the well inspected. The fix is usually a repair plus disinfection, sometimes followed by continuous disinfection equipment the contractor sizes for the well.
Bacteria findings are about the well as much as the water, so the right professional is one who can look at construction and treatment together.
Get matched with a whole-house treatment proPFAS: which limits apply to my result?
Michigan has enforced seven PFAS drinking water standards since August 3, 2020, per EGLE. Compare each compound on your report to its Michigan limit below. Federal limits for PFOA and PFOS arrived in 2024 at 4 ppt, tighter than Michigan's, and the state has signaled its numbers may tighten to follow.
| Compound | Michigan MCL |
|---|---|
| PFNA | 6 ppt |
| PFOA | 8 ppt |
| PFOS | 16 ppt |
| PFHxS | 51 ppt |
| HFPO-DA (GenX) | 370 ppt |
| PFBS | 420 ppt |
| PFHxA | 400,000 ppt |
Michigan PFAS in wells is a point-source story with named places: the Wolverine tannery-waste plume around Belmont in Kent County, the 2018 Parchment emergency in Kalamazoo County, and firefighting foam at the former Wurtsmith Air Force Base in Iosco County, all documented by MPART. If you live near a documented site, test through a certified lab. For results over a limit, granular activated carbon and reverse osmosis are the technology classes designed to reduce PFAS, and plume-area households should also ask MPART and their health department about state-run options before buying anything.
Get matched for PFAS treatmentWhat about the rotten-egg smell?
Hydrogen sulfide rarely appears on a standard report because it escapes samples quickly, so the nose finds it before the lab does. It is a treatable nuisance, and diagnosing whether it comes from the well, the water heater, or bacteria decides the fix. That diagnosis path lives on the sulfur and odor treatment page.
More than one line over a limit?
Michigan reports often fail on several lines at once: iron plus hardness plus odor, sometimes arsenic too. Stacking single-purpose gadgets in the wrong order wastes money, so multi-problem reports are usually a whole-house treatment conversation: one system train, planned around the full report.
Where do I get my well tested in Michigan?
Three routes, all legitimate: your county health department, an EGLE-certified drinking water laboratory, or a state-funded free testing round when one is open. Certified results are the ones health departments accept and contractors can size equipment from.
County health departments
Most run well water sampling programs for residents, sell sample kits, and explain results. They also hold your well's permit records. This is the default starting point, and the cheapest one after the free rounds.
EGLE-certified labs
EGLE certifies drinking water labs across the state and explains how to get your water tested. Order the tests your county's geology calls for: coliform and nitrate annually, arsenic in the Thumb and Southeast, PFAS near documented sites.
State free-testing rounds
When Michigan funded a free round with a $5 million appropriation in 2023, about 15,000 kits were requested in roughly a week, per EGLE (announced October 2023). Rounds open and close, so check EGLE's newsroom, and move fast when one opens.
The full route map, including county programs and what each test costs, lives in the free well water testing guide.
Reading a result in one of these counties?
County pages carry the local aquifer story, the documented data for that county, and the health department contact.
Well test questions, answered
How often should I test my Michigan well water?
EGLE recommends testing every year for coliform bacteria and nitrate as part of routine well maintenance. Arsenic, hardness, iron, and manganese change slowly, so a baseline test plus a recheck every few years, or after any well work, is a reasonable rhythm. Test PFAS if your county has a documented plume or your health department advises it.
My arsenic result is under 10 ug/L. Am I done?
The federal limit is 10 ug/L, so no action is required. The EPA health goal for arsenic is zero, though, so many Michigan households with results in the middle single digits still choose a point-of-use reverse osmosis or adsorption unit for drinking water. That is a judgment call, not an emergency, and retesting first is fair.
Are home test strips good enough for a treatment decision?
No. Strips can flag hardness or iron roughly, but treatment sizing needs numbers from an EGLE-certified drinking water laboratory. Certified labs follow required methods and quality controls, health departments accept their results, and a contractor can size equipment from them. A strip result is a reason to order a lab test, not a substitute for one.
What if my report shows more than one problem?
Common in Michigan: iron plus hardness plus an odor, sometimes with arsenic on top. Treating each finding with a separate gadget usually costs more and works worse than one planned system, because the equipment has to run in the right order. That is the whole-house conversation, and it starts from your full report, not one line of it.
Does a bad test mean I need a new well?
Rarely. Most Michigan findings, including arsenic, iron, manganese, hardness, and nitrate, are handled with treatment equipment matched to the number on the report. A repeat coliform hit can point to a well construction problem worth a contractor visit. Drilling new is the last resort, and it needs the same water testing afterward anyway.