Michigan’s well construction code requires that after construction or repair of a well, the well must be disinfected, and then flushed to waste. The person constructing or repairing the well is required to disinfect the well. After all chlorine is removed from the system, the water well is required to be tested for coliform bacteria. Well owners are responsible for the collection of all required water samples.
Water Sampling of Residential Wells
- Michigan’s well construction code requires a coliform bacteria sample be taken for all new, repaired, and reconditioned wells.
- The coliform bacteria test must show the absence of coliform bacteria.
- District Health Department No. 2 also requires that a nitrate water sample be collected from all newly constructed wells, in addition to the coliform bacteria sample. A partial chemistry sample is highly recommended. The partial chemistry sample will test for: chloride, fluoride, sodium, sulfate, hardness as CaCO3, iron, nitrate, and nitrite.
- Water sample bottles can be obtained free of charge, from the MDHHS lab. They are provided with a shipping container with a mailing address. To obtain water sample bottles, please call 1-800-504-2650 to determine which type of sample you are needing before contacting the MDHHS lab.
- The sample must be taken or mailed to a state certified laboratory. The labs charge a nominal cost for analyzing the water.
- Seasonal wells that are depressurized should be disinfected and sampled prior to consuming the water at the start of the season.
- Annual coliform bacteria sampling is recommended.
Page last updated on June 28th, 2023.
Type III Public Water Supplies
- Two coliform bacteria water samples (taken 24 hours apart) and a nitrate sample (partial chemistry) must be taken after the well is constructed and prior to offering water to the public for consumption. Water must show an absence of coliform bacteria. The maximum level for nitrates is 10.0 mg/l (parts per million).
- Two coliform bacteria water samples must be taken if a water supply is depressurized, such as when it is shut down for the winter.
- Licensed facilities, such as food establishments or campgrounds, may be required to complete annual sampling requirements.
Other water samples may be required by District Health Department No. 2, as part of a well permit requirement: for example, if a water well is near a source of contamination.
Water sampling bottles are available for order by phone, and you may contact the State of Michigan Drinking Laboratory at (517) 335-8184. Water sampling bottles are sent to the State of Michigan Drinking Laboratory in Lansing, or any state certified lab, for analysis. You may ask for the state water kit No. 31, which will test for coliform bacteria in addition to an automated partial chemistry analysis which includes nitrates. Please contact your local health department if you wish to discuss the results of your water samples.