All drinking water wells should be tested for coliform bacteria and nitrates at least annually or if a change in color, taste, or odor is discovered.

Many factors contribute to a safe drinking water supply. To determine if a water well is free from bacteria, it should be sampled. Even if the past sample results indicate safe bacteriological levels, water conditions do change over time. To assure the water is safe; water samples should be collected and analyzed for bacteria when any of the following occurs:

Additionally, high levels of nitrates could be a health risk. Nitrate testing is available through the Environmental Health office, or through a number of certified drinking water laboratories. Check here for a list of certified drinking water labs, or contact us for additional information.

Sampling your drinking water supply
If you are using an onsite water well for your drinking water supply, there are two ways to have your water sampled.

1. The Kalamazoo County Environmental Health staff will sample your well for bacteria, nitrates or other compounds of your choosing. After submitting the Water Sample Request form to our office, you will be contacted to set an appointment.
2. You may also sample the water well yourself. There are a number of certified drinking water laboratories available that can provide testing, click here for a list. Special containers are needed for each water sample, and each lab uses different containers. Please review the guidelines below for good water sampling practice, but always follow any instructions that come with the sampling containers.
   • Do not open the bottle until you are ready to collect the sample.
   • Do not touch the inside of the cap or bottle.
   • Do not rinse the bottles. Some bottles may contain preservatives that need to stay in the water sample.
   • Select a clean indoor faucet, and run the cold water for about five minutes or two pump cycles. Reduce the water flow to a pencil-sized stream. Remove and hold the cap while you fill the bottle according to the instructions provided by the lab. Do not let the cap or bottle touch the faucet. Avoid splashing water.
   • Replace and secure the cap to insure that the sample does not leak.
   • Complete all known information on the form by printing or typing legibly. A separate form is required for each sample bottle.
   • Fold the form and attach it to the bottle with a rubber band.
   • Refrigerate the sample until you are able to deliver it to the lab.

Understanding your drinking water results

Bacteriological Analysis

A bacteriological analysis of drinking water determines the presence of coliform bacteria. Coliform are found in the intestinal tract of warm-blooded animals, surface water, some soils, and decaying vegetation, and are used as "indicator" organisms. If coliform bacteria are present, pathogenic or disease causing organisms could be present. Most drinking water labs use the "defined substrate method" to determine the presence of coliform. A detected (or positive) result may indicate that a water supply is not properly protected from contamination. The test also assesses the presence of E. coli. If E. coli is detected, it is more likely that the water supply may contain disease-causing organisms resulting from fecal contamination. A detected bacteria result indicates the need to chlorinate your water well. You may review the Simple Chlorination excerpt from the Water Well Disinfection Manual produced by the Michigan Department of Environmental Quality.

Nitrate, Partial Chemical and Arsenic Analysis
Table 1 lists four parameters where federal and state agencies have established drinking water health advisory levels for public water supplies. Parameters listed in Table 2 are associated with aesthetic water quality problems.

Test results are reported in milligrams per liter (mg/L), equivalent to parts per million.
¹USEPA drinking water standard is 10 mg/L for nitrates and 1 mg/L for nitrite.
²See DEQ pamphlet EQC2033 "Nitrate in Drinking Water" 2/00
³Optimal range of fluoride concentration per American Dental Association
⁴USEPA drinking water standard is 4 mg/L

Unless your water well is properly designed, constructed, and maintained, a test result conforming to state standards may give you a false sense of security. A poorly constructed well can produce intermittent satisfactory bacteriological results; continued safety of the water supply cannot be assured.