42 million people in the United States depend on wells to supply their households with water. When you have a residential well, you have to be careful about the microorganisms, chemicals, and compounds in the water to ensure that you don’t make yourself or your family ill.

This means consistent water testing and well maintenance. So what if during one of these routine tests you get a positive result for coliform bacteria?

In this article, we’re going to go over exactly what it means when well water tested positive for coliform, what coliform is, and how you can keep your water safe for consumption after a positive test.

What Is Coliform?

Coliform is an umbrella term for a wide variety of waterborne bacteria. Each of these types of coliform bacteria falls into one of three categories: fecal coliform, total coliform, and E. coli.

Can Coliform Hurt You?

Almost all species of coliform are harmless to ingest. However, e. Coli and other types of fecal coliform can cause serious illness if ingested.

What Coliform Indicates About Your Water

So if most types of coliform bacteria are harmless to humans, then why is it a big deal if your well water tests positive for it?

Coliform itself is usually harmless, but it’s known as an “indicator organism.” This means that if coliform is found in your well water, there’s a huge chance that other types of harmful bacteria, parasites, and pathogens are in the water as well.

Also, some types of coliform are harmful to ingest; a positive test for coliform indicates that there could be dangerous organisms in your drinking water.

What to Do If Your Well Water Tested Positive for Coliform

If you get a positive test, the first thing you should do is stop drinking the water. While everything might be fine and the water might still be safe to consume, you don’t want to take that chance.

You can drink the water after bringing it to a boil for five minutes, or you can rely on water bottles.

Resample the Water

You should have your water resampled. Sometimes, you can get a false positive for coliform, so a resampling will double check the initial result.

Have Other Testing Done

You should also have your water tested for other types of bacteria or pathogens since the presence of coliform indicates that there are likely other contaminants in there.

Have Your Well Disinfected

If you get a second positive result and/or discover other contaminants, have your well disinfected by a professional.

Speak to a Professional

On the topic of professionals, you should speak with one ASAP. Not only will they be able to disinfect your water, but they may also be able to find the source of the contamination to prevent this from happening again.

Final Thoughts

If your well water tested positive for coliform, don’t panic yet. There’s a chance that the water is perfectly safe to drink, but you will want to get it tested and disinfected as soon as you can, just in case.

Are you in the Phoenix area looking for some help with your well? We can help. Contact us today with any questions or to set up a consultation.


Do you suspect that your well water is contaminated? We can help! Empire Pump specializes in water testing and contaminated well water treatment to ensure that you have safe drinking water. Call 623-582-5069 now to schedule an appointment or to have your questions answered!

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