Tractor applying pesticides on a wheat field/© Adobe Stock
Pesticides are chemicals designed to kill or control pests, including insects, weeds, fungi, and other unwanted organisms. They play a significant role in agriculture, protecting crops from pests and increasing yields. However, their use can have implications for water quality, especially when it comes to well water.
Pesticides can contaminate well water if they are applied near the well and if the well is not properly constructed or maintained. If a well casing is cracked, it can allow pesticides to enter the well more easily. Additionally, activities such as pesticide mixing and loading near the well can result in the contamination of the drinking water supply. It is important to prevent well water contamination because once the groundwater supplying the well is contaminated, it can be difficult to clean up.
What are the effects of pesticides in well water?
Exposure to pesticides in drinking water can have various health effects, depending on the type and concentration of the pesticide.
Acute effects: Nausea, vomiting, and diarrhea
Long-term effects on the nervous system, reproductive system, or even increase the risk of certain types of cancer.
May contaminate surface water, groundwater, and soil, affecting aquatic life, plants, and animals, disrupting ecosystems and have detrimental effects on biodiversity.
When should I test my well water for pesticides?
If your well is located near farm fields where pesticides are applied or if you suspect pesticides in your water, it is important to regularly test for the presence of pesticides and take appropriate measures to mitigate contamination if detected. This may include implementing proper agricultural practices, using alternative pest control methods, or installing water treatment systems.
What treatment should I use if there are pesticides in my well water? How do I remove pesticides from my well water?
Once you test and have decided to treat your water to remove pesticides, the Minnesota Department of Health has developed a Home Water Treatment Guide that covers treatment for any common constituent in well water. The most important advice we can provide you is if you are going to add treatment to your home water system, be sure the treatment device has been certified to remove iron by an independent third-party certification organization.
Where can I get local help and information about pesticides in my well water?
Contact your local health department – They can help you interpret your sample results and may have information on the best treatment options for your situation. If they personally aren’t able to answer your questions, they will know who to contact who will be able to help you, likely at your state health department.
Contact a water treatment professional – We would recommend contacting a water treatment professional who has been certified through the Water Quality Association’s Professional Certification Program.
State or Federal Geologic or Water Resource Agency – They may have completed field studies of your area or collected samples from water wells to map and understand the water quality in your state. In addition, they may house water well logs, including yours, or be able to provide additional information about the aquifer your well is getting water from.
Consult your well driller or drilling contractor – The contractor that drilled your well, and other local contractors, may be aware of the water quality issues nearby including pesticides, and might have worked with other well owners in your area to solve this issue.
Research online – You should be inquisitive; it will help you significantly because there can be great information available online. Use search terms like “my state (CA, ME, IL, etc.) water well logs,” “my state groundwater quality,” or “my state well water quality.”
Contact us directly – If these other local sources don’t work out for you, we may be able to help. We may be able to provide direct assistance, and/or direct you to a technical assistance provider in your area who can help answer your questions (This is a free service funded by USEPA).
Additional Resources
Drinking Water and Pesticides. US Environmental Protection Agency.
Pesticides in Drinking Water. 2019. Wisconsin Department of Natural Resources.
Pesticides and
Pesticides and Water Quality. Water Resources Mission Area. US Geological Survey.
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Sign up for the free 10-week email course from PrivateWellClass.org. The class is a project of RCAP and the University of Illinois, with funding from USEPA.
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