How to Test Water for Bacteria: 2022 Ultimate Guide

If you get your water from a private well, there’s always a risk that it may contain bacteria.

Public water supplies are required to implement disinfection programs and procedures and maintain official records.

In public water sources, bacteria are killed during disinfection. If you don’t disinfect your well water before drinking, there’s a risk that you might end up getting sick from a bacterial disease.

In this guide, I’ll be sharing the information you need to know about bacteria in drinking water, including how to test for bacteria and which types to test for, and what to do if you discover bacteria in your well water.

🦠 How Does Bacteria Get Into Well Water?

There are a number of factors that make well water more susceptible to bacterial contamination. The most common is an old or poorly constructed well – if your well is cracked or not properly sealed, coliform bacteria may be able to get into the well’s aquifer.

If you live near a septic tank or farm, you’re at greater risk of drinking bacteria-contaminated well water.

🔬 How Often Should I Test My Water for Bacteria?

Regardless of whether you suspect bacterial contamination or not, you should get your well tested at least once a year for coliform bacteria. It’s also good practice to check your well every spring for mechanical issues. It’s often cheaper and easier to prevent bacteriological contamination than to deal with a long-term contamination issue.

If you’re concerned about bacteria in your local area, consider contacting a representative of your local health department. They should be able to tell you more about the risks of surface water or groundwater containing bacteria in your local area.

You should also test your well water if:

  • You have experienced a recent natural disaster locally, such as earthquakes and flooding;
  • You live near a waste disposal site or farm;
  • Your drinking water quality changes (in odor, taste, color, etc.);
  • You perform maintenance on your well, such as repairs or replacement  of parts.

🧫 Which Bacteria Should I Test For?

There are three types of bacteria you should get your well water tested for: total and fecal coliform, and E. Coli.

Total Coliform Bacteria

Total coliform bacteria is a type of microbe found in soils, plants, surface water, and in the digestive systems of warm-blooded animals. While coliform bacteria doesn’t usually make you sick if you consume it, the presence of these precursory bacteria in your water indicates that the possibility exists that disease-causing microorganisms are also present. The higher the total coliform count, the greater the chance that harmful germs like parasites, viruses and bacteria are also present in your water.

Coliform Bacteria

Fecal Coliforms

A common type of total coliform is fecal coliform. This bacteria can be found in the digestive systems and feces of warm-blooded animals. Again, fecal coliforms are usually harmless, but if your water comes back positive for these bacteria, it’s usually a sign that it is contaminated with feces. Feces contains other harmful germs that can cause dysentery, diarrhea and even hepatitis.

Fecal Coliforms

E Coli Bacteria

Escherichia Coli (E. Coli) is part of the fecal coliform group. Again, this bacteria is found in the environment, some foods, and the intestines of warm-blooded animals. Most strains of E. Coli are actually harmless, but some can make you sick. E. Coli may cause UTIs, pneumonia, diarrhea, and respiratory illness, according to the CDC.

E Coli Bacteria

🔎 How to Test Well Water for Bacteria

Testing your well water for bacteria is difficult to do with an at-home or DIY test. Most bacteriological water testing kits require a minimum 48 hour incubation period before accurate results can be made available. While you can test for other contaminants like chlorine and heavy metals yourself, I would highly recommend having  your water tested for microbiological impurities by an expert.

Certified Laboratory Testing

The best option for accurate bacteria testing is to use a certified laboratory. Certified lab testing can give you clear, detailed results, providing an in-depth insight into whether your water contains bacteria, and how much.

My recommended certified lab for testing is Tap Score by SimpleLab. There are several SimpleLab test packages for bacteria to choose from, including the Universal Bacteria Genetic Identification Test, which tests for “all bacteria at the DNA level”. If you’d prefer to test for multiple contaminants at once, you could instead purchase the Essential Well Water Test, which tests for total coliforms and E. Coli. 

tap score water testing

When you purchase a bacteria test kit from SimpleLab, you’ll receive a package in the post with sampling vials and instructions for collecting  a water sample. You’ll then mail your water sample to SimpleLab and receive your test results via email. You can expect to receive test results within 5 days.

State & Local Health or Environmental Department

Most states and local health departments offer testing for fecal and total coliforms. Getting your water tested by your state isn’t usually free, so you may prefer to choose from a bigger selection of state-certified laboratories in your area instead. Most local environmental or health departments should list the licensed laboratories in your local area on their website.

❓ What Should I Do If My Water Tests Positive for Bacteria?

If your drinking water has tested positive for bacteria, stop drinking it immediately and switch to a bottled water supply.

In the meantime, try to find out whether the contamination is an isolated incident or a continual problem. For instance, has local flooding or an earthquake contaminated your well? Or does your well need repairing to prevent contamination in the future?

This may be a good time to contact a licensed water treatment professional to properly evaluate your situation, identify issues, and to recommend possible solutions.

If you’ve determined a problem that needs to be fixed to ensure water is safe to drink in the future, work on fixing this as soon as possible. You should also use a disinfectant like chlorine to kill the coliforms,  utilizing the services of a water treatment specialist or a licensed well contractor if you don’t feel comfortable doing it yourself.

Once you’ve disinfected your well and remedied any problems that may have caused the contamination, you can test for total coliforms once more. If no bacteria presence is detected in your sample, you’re safe to drink your water again.

water testing with tap score

Note that there may be occasions where you need to implement a longer-term water treatment solution. If your drinking water is contaminated with E. Coli or total coliforms, and you have no means of preventing this contamination, or you just want to stay on the safe side, using a purification system that can eradicate and remove microbiological impurities is highly recommended .

There are several water treatment options to consider for removing E. Coli, total coliforms and fecal coliforms:

Automatic Chemical Feed Systems

A properly installed and maintained feed system utilizing a simple diluted household bleach solution or a hydrogen peroxide dilution will neutralize the vast majority of naturally occurring bacteria and other pathogens. Chlorine can also provide extended residual protection throughout the entire connected plumbing system.

us water systems chlorine injection system

UV Purifiers

UV purifiers are an increasingly popular choice for killing pathogens, including coliform bacteria, in water. A UV water system is typically installed at a cold water line, either at a home’s point of entry or in a point-of-use location, such as underneath a kitchen sink. UV purifiers produce ultraviolet light, which alters the DNA of pathogens and kills them. It also prevents them from reproducing. UV, however, does not provide residual disinfection.

viqua d4 premium

Reverse Osmosis

Reverse osmosis systems, when properly maintained and serviced, remove more than 99.9% of total dissolved solids present in drinking water, including health-affecting pathogens like E. Coli, and fecal and coliform bacteria. An RO water system forces water through a semipermeable membrane, which contains a large number of tiny pores that only water particles can pass through. Manufacturers, however, caution against connecting an R.O. system to any water source that is microbiologically unsafe.

Reverse Osmosis System

Boiling Water

The simplest and most affordable method of removing coliforms and other pathogens present in water is to boil your water before drinking. Bacteria can’t survive above 149°F, so if you’re only dealing with the presence of pathogens, boiling your water will do the job. However, it isn’t convenient to have to boil your water every time you want to drink it, which is why many people choose a water system that kills or removes coliform bacteria instead.

Looking to learn more about the best treatment options for coliforms? Take a look at my guide on the best water filters for coliforms here.

🧠 Frequently Asked Questions

Why can’t all water filters be used to remove bacteria?

Most types of bacteria, including coliform and E-Coli (Escherichia coli), are very small – almost as small as water particles themselves. This means that a standard water filtering solution, which improves water quality by filtering out metals, chemicals and other particles, may not have small enough pores to filter out smaller organisms. As a result, these organisms will end up passing through the filter with water particles, which is why a more specialized purifying system is often needed instead. Also keep in mind that even those micro and nano filtration elements that are small enough to remove these contaminants only trap them and do not kill them.

Should I test for bacteria in a city water sample?

Rarely if ever. The presence of bacteria is highly unlikely in city water. Any bacteria present in surface or ground water should be effectively removed by your water supplier before this water reaches your home. The only time your water may test positive for microbiological contamination is in the instance of damage or breaks in the main water line, in which case, a boil water notice will be issued while your local authority remedies the problem.