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Home > Protecting Our Lands & Waters > Water Protection > Private Well Testing for Pesticide Contamination > Private Well Pesticide Testing Options

Private Well Pesticide Testing Options


Laboratory Options

  • The Minnesota Department of Agriculture has developed a Tables of Laboratories, Analytical Capabilities and Contact Information (PDF: 55 KB / 2 pages) that can help a well owner determine which screens, tests or analyses might be useful in testing a private well. Additional information about these analyses is presented below:
    • Low-cost immunoassay screens    – These tests range from $25 to $50 and are commercially available for atrazine and acetanilide herbicides (such as acetochlor). They are qualitative and should not be relied on for actual concentration values but still give a more accurate result than an in-home test kit. They can provide an indication – within a limited range of concentrations – of possible contamination from groups of pesticide active ingredients and several of their breakdown products (e.g., they can identify that "atrazine-like" chemicals are present, but cannot identify the specific chemicals responsible for positive test results).  What is an immunoassay screen?
    • Moderate-cost quantitative tests  – These tests can be $125 or more, and offer precise identification of specific pesticides. Depending on the test, certain pesticide breakdown products may be reported. Laboratories conducting these tests may not be certified to report results for safe drinking water comparisons in Minnesota. Their minimum reporting limits may not include concentrations of interest, and their results are typically not verified against national drinking water standards.
    • High-cost, certified quantitative analysis  – Certified quantitative laboratory analysis can cost $350 or more. These laboratories are certified to provide quantitative reporting of pesticide concentrations at very low levels, suitable for establishing the safety of drinking water. The number of pesticides for which they can provide results is typically smaller than those employing moderate-cost quantitative tests. These laboratories rely on sophisticated equipment and EPA-approved safe drinking water methods. 

In-Home Option for Atrazine

  • Watersafe® Pesticide Test kit- This EPA verified immunoassay in home test kit costs about $10 and is only capable of providing a very general assessment of atrazine’s presence in your well water.  During EPA verification, the test always showed a positive result when the concentration of atrazine was 3 ppb or higher but when used to test water with a concentration of 1 ppb it occasionally gave a positive result. 

What Is an Immunoassay Screen?

Immunoassay tests "screen" a water sample for specific pesticides. They provide an indication that certain pesticides might be present, but they cannot confirm their precise concentration.  They can sometimes detect other pesticides or pesticide breakdown products, although typically to a significantly lesser degree. Immunoassay screens are a low-cost alternative to more expensive tests and analyses. Detection limits for the screens are suitably low enough for water testing, but the screens are not an absolute indicator of the exact quantity of a pesticide or of drinking water safety. 

Available immunoassay screens and most commercially available quantitative tests and analyses cannot detect many pesticides or breakdown products that may be contaminating a private well.  Nevertheless, results of qualitative immunoassays or quantitative tests and analyses may help determine if routine screens, tests or analyses are warranted to verify any health concerns.  

  • How immunoassay screens work:  A water sample is added to a small tube with antibodies that coat or adhere to the tube walls followed by a chemical that reacts with enzymes released by the antibodies. This chemical changes color in response to the enzymes. The amount or extent of the color change in the solution is directly related to a specific contaminant concentration. The color is compared to the color change of a known concentration sample.  This test and the color comparisons are done in the laboratory by skilled professionals with specialized equipment, not by the homeowner. 
MDA Contacts

Joe Zachmann
651-201-6588
joseph.zachmann@state.mn.us

Pesticide & Fertilizer Management Division