My Well Water Tested Positive for Coliform: What Do I Do?

Finding coliform bacteria in your well water can come as a nasty shock. But don’t panic – removing this harmful microorganism and making your water safe to drink is pretty simple.

In this guide, we’ll share everything you need to know about coliform bacteria in well water, including how this pathogen gets into water supplies, why it’s so dangerous, and how to eliminate it from your water supply.

๐Ÿ“– TL;DR

For a temporary solution: shock your well. For long term protection: install a disinfection system such as a UV purifier or chemical feed pump.

๐Ÿฆ  What Is Coliform Bacteria and How Does it Get Into Water?

Coliform bacteria is a type of bacteria that’s present in the digestive systems of humans and animals, and is found in their waste. Coliform bacteria are known as “indicator” organisms because they typically indicate the presence of harmful pathogens like E. coli.

There are several paths that coliform bacteria can take to contaminate well water:

  • Through surface water runoff or floodwater
  • Through broken or cracked well components
  • From leaking septic tanks
  • From agricultural runoff containing manure

Under normal conditions, coliform bacteria should never contaminate a well. However, if the well is old or poorly constructed, the well floods, or a nearby septic system overflows, coliform bacteria may enter your well water supply.

water test came back positive for coliform

๐Ÿงซ Is Coliform Bacteria Harmful?

Most coliform bacteria aren’t disease-causing. However, some rare E. coli strains can cause serious gastrointestinal illness.

๐Ÿ’ก While coliform bacteria itself is usually safe to drink, it often indicates that dangerous, disease-causing bacteria and other pathogens are present in water.

So, if a sample of your water contains fecal coliforms, you shouldn’t drink it – especially if you have infants, the elderly, young children, or people with compromised immune systems living in your home.

๐Ÿ‘จโ€โš•๏ธ How Much Coliform Is Safe?

Wondering what amount of coliform is considered too high?

The Environmental Protection Agency (EPA) has set a Maximum Contaminant Level Goal (MCLG) of 0 for fecal coliform. That means that no amount of coliform is considered safe in water – because even traces of this bacteria could indicate fecal contamination.

๐Ÿ“ What to Do If your Water Tested Positive for Total Coliform

If your water tests positive for total coliform or fecal coliform, do these three things:

  1. Stop drinking your water immediately or boil your drinking water to make it safe to drink. (You can still shower in water after a positive test result for coliform contamination, as long as no water is ingested.)
  2. Treat the bacterial contamination with shock chlorination (more on that below).
  3. Test your water again to ensure the total coliforms are gone. If you get another positive coliform test result, shock chlorinate your well again.
Instrument for testing well water

๐Ÿงช How to Remove Coliform Bacteria From Well Water

Temporary Solution: Shock Chlorination

Shock chlorination is the best temporary solution to eliminate total coliform. If total coliform has entered your well water system by chance or due to a one-off occurrence, like flooding, shock chlorination may be the only water treatment method you need.

Shock chlorinating your well involves introducing high levels of chlorine into your water to kill pathogenic bacteria and other organisms. You can use dry chlorine pellets, liquid bleach, or chlorine granules to shock chlorinate your well. Once you’ve shock chlorinated your drinking water, you’ll need to test a water sample again to check that the treatment has worked.

Shock Chlorination
Source: University of Georgia Extension

Chemical Injection

Chemical injection is a popular method of continuous disinfection for a well water supply. To protect your well water system from fecal contamination 24/7, a chlorine injection system is a reliable option to choose.

๐Ÿ’ก How does a chlorine injection system work? This type of water treatment system is installed at your home’s water point of entry, close to the pressure tank, and injects a measured amount of chlorine into your water. Water is stored in a tank to allow the chlorine to disinfect it, before flowing into your home’s plumbing system.

Some chlorine injection systems have a final treatment stage containing carbon media, which removes the chlorine from the disinfected water, improving its taste.

Springwell chemical injection system

UV Purification

UV purification is a straightforward method of killing total coliforms and other pathogenic organisms with ultraviolet light. If total coliforms are naturally present in your water, UV purification will provide you with around-the-clock reassurance that your water is safe to drink.

A UV system uses a UV lamp in a sleeve. Water flows through the UV chamber, and the ultraviolet light from the lamp deactivates the pathogens and prevents them from reproducing or causing water borne illness.

UV is a low-maintenance purification solution, only requiring one UV lamp change per year.

See our top recommended UV purification systems in 2022 and read our reviews here.

Uv lamp on table

๐Ÿ“– How to Reduce the Risk of Coliform Bacteria Contamination in Wells

Routinely Pump Septic Tanks

If you have a private well and septic system, poor maintenance of your septic system could cause disease-causing organisms to enter your well supply.

The general rule is that your septic tank should be pumped and emptied every three to five years, but this depends on how many people live in your home.

Signs your septic tank need to be emptied are:

  • Water pooling around your drain field and tank
  • Appliances like toilets draining slowly
  • Sewage backing up into your property

Leaking septic systems are one of the biggest causes of groundwater and well water contamination, so make sure to keep on top of your septic tank upkeep to prevent this issue on your property.

Ensure the Well is Raised

To prevent flood water from pooling in the well, make sure the well is located on raised ground.

This is difficult to achieve if your well is already built. However, your local well contractor may be able to raise your well, so talk to them if your well is currently located in a ditch or at the bottom of a hill.

Installing a well on a raised surface means that water will run away from the well, preventing surface runoff into your well system.

Required distance of well water from septic tank
Source: Mississippi State University Extension

Test Your Water

If you know that your well water contains coliform bacteria, good for you – it means you’ve tested your water, which is essentially the only way to detect this tasteless, odorless contaminant.

It’s recommended by the EPA to test your water at least once a year for coliform bacteria and other common well water contaminants. You should also test your water if you have reason to believe it may be contaminated by bacteria, such as if any members of your family have suffered from recurring gastrointestinal illness.

Take a water sample and test it for the three following bacteria:

  1. Total coliform bacteria, which is found in soil, and human or animal waste.
  2. Fecal coliforms, a group of total coliforms that are typically found in the feces of warm-blooded animals.
  3. Escherichia coli bacteria (E. coli), which is the most major fecal coliform species. Because it’s rarely found naturally in the environment, E. coli is the biggest indicator of fecal pollution.

Routinely testing your water is one of your best defenses against pathogens. If testing detects coliform bacteria, you know what to do: follow the steps in this guide to treat your water as soon as possible.

counting total coliforms

๐Ÿง  My Well Water Tested Positive for Coliform: FAQs

What does coliform in well water mean?

Coliform in well water often means that your water has been contaminated by human or animal waste. If your drinking water contains coliform, you’ll need to get rid of the bacteria and drink bottled water in the meantime.

How serious is coliform in well water?

The severity of coliform in well water depends on how much coliform is present. Any coliform detected above 0 is concerning. High levels of coliform indicate that your drinking water could cause serious gastrointestinal illness.

Can you shower in water with coliform?

Yes, you can shower in water with coliform. The risk of disease from showering in water containing E. Coli or other bacteria is slim. Just make sure you don’t ingest any of the water until your total coliform count goes back to 0.

๐Ÿ“‘ Takeaway

Getting a positive test result for E. Coli or any other species of the fecal coliform group can be disturbing. Nobody wants to drink water that’s potentially contaminated by animal or human waste – and thankfully, nobody has to.

If you discover coliforms in your water, treat your water with shock chlorination, then conduct another water test to check that the bacteria has gone. Consider a long-term solution, like UV purification or chemical injection, and take every effort to protect your well system from contamination. If you’re unsure about why your well water is contaminated, contact your local health department.