City Water vs Well Water: Different Tests, Different Risks
City water and private well water are managed differently, so
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Michigan requires testing when a private residential well is constructed, and state guidance calls for coliform bacteria testing before a newly installed or repaired well goes into service. Beyond that, some requirements depend on where the property sits and why the water is being tested, including certain real estate transactions.
Michigan does not impose one blanket annual testing mandate on every private well owner. The state recommends a routine testing schedule, and that schedule is guidance, separate from the legal requirements above.
This guide from ETR Laboratories covers Michigan’s requirements and its recommended schedule. It also explains the role of local health departments and what to confirm before testing for a home sale or another official purpose. To see how Michigan compares with other states, our state-by-state guide to well water testing requirements lays out the rules nationwide.
Four points summarize where Michigan draws the line between required and recommended testing:
Michigan requires testing when a private residential well is first installed, and it requires coliform testing when a well is repaired. Some real estate transactions also carry testing requirements, depending on location. The two sections below cover each situation.
When a private residential well is installed or repaired, Michigan EGLE guidance requires the well to be disinfected and an initial sample to show the water is free of coliform bacteria before the well is put into service.
This requirement checks for bacterial contamination introduced during drilling, construction, repair, or disinfection. It is a narrow bacteria check, and it does not screen for every possible contaminant.
If that first sample comes back positive for coliform, the well typically needs to be disinfected again and resampled before it goes into service. Your well driller or local health department will direct the next step, so keep both in the loop until you have a passing result.
Local sanitary codes can be stricter than the state requirement. Check with the health department that covers your property before assuming the statewide coliform test is the only rule you need to meet.
Michigan has no single statewide rule requiring the same well water test for every residential sale. Testing may be required depending on where the property is located and which local health department covers it, and other parties in the transaction may add their own conditions.
A lender, for example, may set requirements for:
If you’re buying or selling a Michigan property with a private well, confirm those requirements with the local health department and your lender before anyone collects a sample. Testing the wrong parameters or sampling too early can mean repeating the process. Our guide to well water testing when buying or selling a home covers lender requirements and sample timing in more depth.
Michigan’s routine recommendations go beyond the testing legally required for new and repaired wells. The Michigan Department of Health and Human Services (MDHHS) currently recommends this schedule for private residential well owners:
| How Often | What to Test |
| Every year | Coliform bacteria and E. coli, nitrate, nitrite |
| Every 3 to 5 years | Arsenic, lead |
| At least once | PFAS |
These are recommendations for staying aware of your water quality. They are not a universal annual legal mandate for Michigan private wells. The schedule also lines up closely with federal guidance on private well testing, which calls for yearly bacteria and nitrate checks.
Michigan also recommends extra testing when circumstances around the well change, including when:
If one of these applies, your local health department can help you decide which parameters fit your property before you order a broad panel you may not need.
Keep a copy of every report you receive. Results from past years make it easier to spot a change, such as a nitrate level creeping upward, and they give a local health department or lab useful context if a problem appears. When you want help reading a result, EGLE points well owners to its Be Well Informed online tool, and your local health department can explain what a number means for your household.
Michigan directs private well owners to their local health departments because groundwater conditions and land use differ across the state, and so does known contamination. Local permitting rules differ too. Two Michigan homeowners can face different testing requirements while living under the same statewide framework.
As with many state well water laws, the statewide rules are only part of the picture. A local health department may recommend extra parameters because of known groundwater concerns in its area, and a real estate transaction may trigger a local testing requirement that doesn’t apply statewide.
Local health departments are also the office most Michigan well owners deal with day-to-day. They handle well construction permits and inspections, which makes them the first call for property-specific questions.
Treat any state-level summary, including this one, as a starting point for your address. EGLE advises private well owners to contact their local health department with questions about results and next steps. If you’re testing to meet a lender or transaction requirement, confirm the required parameters before you order.
Michigan’s recommended schedule includes bacteria, nitrate and nitrite, arsenic, lead, and PFAS because each can affect private well water quality in the state, and each follows its own timeline.
Arsenic is a particular concern because it occurs naturally in Michigan groundwater in parts of the state. Nitrate and nitrite levels can shift with conditions around the well, such as fertilizer use and septic systems. Lead works differently, since plumbing materials can add lead after water enters the home. Those differences explain why the state recommends separate intervals for each parameter.
This page focuses on requirements and schedules. For a contaminant-by-contaminant breakdown, our guide to Michigan well water testing and what to test for covers each parameter and what else Michigan homeowners may want to consider.
The table below summarizes common Michigan situations. “Recommended” means the state advises testing without describing it as a routine legal mandate for every private residential well.
| Situation | Required or Recommended? | What to Test | Who to Check With | Official Source |
| New or repaired private well | Required | Coliform bacteria before the well is placed into service | Local health department | Michigan EGLE: Private Well Testing |
| Routine homeowner testing | Recommended | Coliform/E. coli, nitrate, and nitrite annually; arsenic and lead every 3 to 5 years; PFAS at least once | MDHHS or local health department | MDHHS: Care for MiWell |
| Real estate transaction | Varies by location and transaction | Depends on local rule, lender, or buyer requirements | Local health department and lender | Michigan EGLE: Private Well Testing |
| Flooding, repairs, or changes in taste, color, or smell | Recommended; repaired wells carry a coliform requirement | Depends on the event and local guidance | Local health department | MDHHS: Care for MiWell |
| Locally identified contamination concern | Varies | Depends on the contaminant or concern | Local health department, EGLE, or MDHHS | MDHHS: Care for MiWell |
Already know which requirement applies to you? Confirm the required parameters with your local health department or lender first, then compare our well water testing options to find a panel that covers what you need.
Once you know what needs testing, the next step is choosing where to send the sample. For routine homeowner testing, your options include:
Whichever route you choose, the way the sample reaches the lab affects the result. Every analysis has a maximum holding time between collection and the start of testing, and bacteria samples in particular need to arrive quickly and cold. A few habits help your sample arrive in usable condition:
The right choice of lab depends on why you’re testing. If a lender or permit office requires a particular credential or collection procedure, verify those conditions before you send the sample anywhere. Our guide to well water testing near me and how to find a certified lab explains how to check a lab’s credentials and testing scope. If no suitable lab is close by, our guide to how mail-in water testing works explains how a properly collected sample gets from your tap to the lab and back as a report.
Michigan recommends annual testing for coliform bacteria, E. coli, nitrate, and nitrite. The state’s guidance does not describe that schedule as a universal annual legal requirement for existing private residential wells. New and repaired wells carry specific testing requirements, and additional rules may apply locally or because of the reason you’re testing.
Oversight is shared. EGLE sets well construction requirements and provides statewide drinking water guidance and laboratory services, while MDHHS provides health-focused testing recommendations and programs. Local health departments help homeowners interpret local requirements and may administer rules within their jurisdiction, so both a statewide source and your local health department can apply to your situation.
Michigan’s statewide guidance does not require the same well water test for every home sale. Testing may be required based on location, and a lender or another party in the transaction can set its own conditions. Before collecting a sample, ask the local health department and your lender what they require, including parameters, lab credentials, collection process, and the acceptable age of results.
If a local rule or lender calls for testing and it isn’t completed, closing may be delayed until the requirement is met. Any consequences beyond that depend on the specific requirement, so confirm the procedure with the organization requiring the test well before closing. Our guide to real estate well water testing walks through the transaction process in more detail.
Free testing exists through specific state projects, but it isn’t available to every well owner at all times. MDHHS’s Care for MiWell Sampling Project, for example, provides free testing to randomly selected private well households that receive an invitation. EGLE also ran a free testing program for private well owners, though its initial funding was exhausted in 2024. Eligibility and funding change, so check current EGLE and MDHHS resources or your local health department before relying on a program.
Michigan well testing starts with why you’re testing. Legal compliance and voluntary monitoring call for different approaches:
Once you know your purpose, ETR Laboratories’ well water testing options let you choose a panel whose analytes match what you need to answer. If your search for well water testing near me turns up no local lab that fits, our mail-in panels ship nationwide.
City water and private well water are managed differently, so
When your ETR Lab’s water test kit arrives, the first
Water testing ads usually talk about the kit in your
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