The Health Metric Bacteria Test is a safe and easy-to-use kit that enables you to test your drinking water from home. This kit can be used to test well water and municipal water supplies for the presence of coliform bacteria. While the test requires no special skills, this EPA-approved method is very sensitive and requires a few precautions to ensure that the results are accurate.
What is coliform bacteria?
Total coliform is a large collection of different kinds of bacteria. Fecal coliform are types of total coliform that exist in feces, and E. coli is one of the subgroups of fecal coliform. Most bacteria tests (including the Health Metric Bacteria Test) are designed to test for the presence of total coliform bacteria.
If the test is positive, it is likely that E. coli or another type of fecal coliform is present in the water, and so the source should be analyzed further in a lab. If the coliform test result is negative, there is no coliform, E. coli or otherwise, in the water.
Preparing for the coliform water test
Coliform bacteria are naturally present in the environment, which makes it possible to accidentally contaminate a water sample and cause a false positive result.
Thoroughly wash your hands before starting the test. Do not open the jar until you are ready to take a water sample. Faucets can be contaminated with coliform bacteria, as it is common for faucets and aerators to get touched or splashed with water when dirty hands are being washed. A contaminated faucet can cause a false positive test for your water supply. Here’s how to avoid contamination:
- Wipe down the faucet and aerator with alcohol or dilute bleach.
- Wait five minutes.
- Flush the faucet for 30 seconds before taking a water sample.
Taking the water sample
- Open the jar and place the cap on a clean surface. The jar contains a harmless nutrient powder. Do not touch the lip of the jar.
- Turn on the cold water until it flows at a slow rate – if the water is running too quickly, you may accidentally overfill the jar.
- Hold the jar under the stream of water and fill it to the shoulder (rounded upper edge), not to the top.
- Hand-tighten the cap onto the jar, being careful not to touch the inside of the cap.
- Shake to mix the powder. It is okay, if some powder remains undissolved.
- As you are shaking it, the liquid in the jar will turn purple.
Waiting for the test results
Place the jar in a “warm” environment, out of direct sunlight. The ideal temperature is 68˚F–90˚F (20˚C–32˚C). Leave the jar undisturbed for 48 hours. If coliform bacteria are present, they will undergo rapid growth, causing the liquid to change from purple to completely yellow within 48 hours.
Observing the test results
After 48 hours, view the jar under normal lighting. Do not shine a light through the jar to see the color as this can change the hue. If the liquid is purple or pinkish, the test is negative. This means you do not have coliform bacteria in water. If the liquid is completely yellow throughout the entire jar, the result is positive (the test is very sensitive and will turn completely yellow in under 48 hours if coliform is present).
Discard the test after 48 hours. If the jar is kept longer than 48 hours, the nutrients in the test will decompose and cause a yellow color to appear within several days. This is not a positive result! You should discard the test after 48 hours.
Need help interpreting the results?
If you have any questions or need help interpreting a test result, please contact our US-based tech support at firstname.lastname@example.org.
Health Metric Bacteria Test Kit
EPA-approved testing method for testing coliform bacteria in water
Wells and other private drinking water sources can easily become contaminated with disease-causing bacteria, putting you and your family at risk of illness.
This test kit allows you to test any water source and compare the results to official EPA standards. Within 48 hours, you can find out if your drinking water contains coliform bacteria or not and act accordingly. Find out more.