Why should I test my private well annually?

Water testing is an inexpensive and effective way of assuring a safe and healthy water supply. It’s estimated that 20-25% of Wisconsin wells have bacterial contamination. Oneida County Health Department advises all private well owners to have their well water tested for coliform bacteria and nitrates annually, especially if infants under six months of age or women of childbearing age drinking the water, or sooner if changes in taste, odor or appearance are noticed, or there is an unexplained illness.

Oneida County Health Department’s state certified Water Analysis Lab provides convenient, reliable, and reasonably priced well water testing for both home and vacation properties. This service is available to anyone; you do not need to be a resident of Oneida County. Lab tests completed on-site include coliform and E-Coli bacteria, with definitive results within 48 hours. Through a partnership with UW-Oshkosh, Oneida County Health Department’s Water Analysis Lab offers additional testing options including nitrates, nitrites, and arsenic. Test kits from other public labs are available at the front desk, fees may apply.

Oneida County Public Health Department Water Fees (updated 1/14/25):

Coliform Bacteria Nitrate-nitrogen Arsenic Buy all 3 kits Buy Bacteria & Nitrate

$27.00 $30.00 $35.00 $82.00 (SAVE $10.00) $52.00 (SAVE $5.00)

** Other testing options available, fees vary by lab.

How do I test my private well water?

To test your private well water:

• Obtain water sample bottles, instructions, and a water analysis form from the Oneida County Health Department at 100 W. Keenan St, Rhinelander.
• Collect your water sample by following the step by step instructions on the back of the Request for Water Analysis form and use the following videos for guidance.
• Submit your water sample to the Health Department within 24 hours of collection. Submission must include the water sample(s), Request for Water Analysis form, and testing fee to the Oneida County Health Department during the following hours:

Monday through Wednesday 8:30 am – 3:30 pm
*Schedule is subject to change during holidays.

Need assistance on how to properly take a water sample? Click on the links below for guidance on how to take a coliform bacteria or nitrate-nitrogen sample from your home.

• Coliform Bacteria Sampling Video
• Nitrate-Nitrogen Sampling Video

You may also contact one of the environmental health team members at [email protected].

Private Well Toolkit

Additional Information for Private Well Owners:

For more information, please see the links below:

• Tests For Drinking Water for Private Wells
• Bacterial Contamination of Drinking Water
• Nitrate In Drinking Water
• You & Your Well updated 11/8/2023
• Iron Bacteria Problems in Wells updated 11/8/23
• Treatment Devices for Private Wells updated 11/8/23

General Information:

For more information, please see the links below:

• Environmental Protection Agency information on groundwater and drinking water
• WI Department of Natural Resources information on groundwater and drinking water