Drinking Water

Well Water

There is concern that if your home in Scio Township is near the plume and has a well, that you could be exposed to 1,4-dioxane in your drinking water. For this reason, the Michigan Department of Great Lakes, Environment and Energy (EGLE) contracts with the Washtenaw County Health Department to conduct long-term monitoring of drinking water wells around the plume to ensure levels are below drinking water criteria. Approximately 375 drinking water wells have been sampled in this state-funded monitoring since 2014.  

New detections in Scio Township drinking water wells farther north than previously known were found startiWell Headng in 2021. Please click here for a map showing locations sampled and where detections were found.

If you would like more information about the proximity of your well to the plume, including a review of your well drilling record and information on the depth to contaminated groundwater in your area, or information on where to have your well tested for 1,4-dioxane, please contact Jennifer Conn at 734-222-3855.

Municipal Water

If you live within the Ann Arbor City limits you are connected to the City's municipal water supply. Within the city limits there is an institutional control called the "Prohibition Zone" that restricts groundwater use in order to prevent exposure to contaminated groundwater. Properties within the Prohibition Zone should not be using well water for any reason. This means no irrigation wells or open-loop geothermal heat pump systems.

The City of Ann Arbor's municipal water supply, most of which comes from Barton Pond in the Huron River, is sampled monthly for 1,4-dioxane. 1,4-dioxane has been detected in the City's municipal water supply, but at levels below the laboratory reporting limit. The laboratory reporting limit is the smallest amount of a substance that can be accurately measured by the laboratory tools. 1,4-dioxane has been detected at levels up to 0.059 parts per billion (ppb), below the reporting limit of 0.07 ppb and more than 100 times lower than the drinking water criteria of 7.2 ppb. The City's monthly 1,4-dioxane sampling results can be viewed on their Water Treatment webpage under 'Keeping Our Customers Informed: Dioxane.'

What if I want to test my water?

If your well water is not already being tested but you would like to test it, you are responsible for any cost. There are two laboratories located near our community that can run tests for 1,4-dioxane. The laboratories are listed below:

Ann Arbor Technical Services (ATS)*
290 S. Wagner Road
Ann Arbor, MI 48103
[email protected]

Method Detection Limit**
for 1,4-Dioxane: 0.3 ppb
EGLE Drinking Water 
Lansing, MI
[email protected]

Method Detection Limit**
for 1,4-Dioxane: 0.5 ppb

Berkeley, CA

Method Detection Limit**
for 1,4-Dioxane: 0.337 ppb

* Please note that only the EGLE Drinking Water Laboratory provides copies of results to the Washtenaw County Health Department. If you use any other laboratory and you would like your results to be kept on file with Washtenaw County, please contact Jennifer Conn with the Washtenaw County Health Department.   

** The Method Detection Limit (MDL) is the lowest measured concentration of a substance that can be reported with 99% confidence that the analyte concentration is greater than zero.