How to Remove Bacteria From Drinking Water

How to Remove Bacteria From Drinking Water

Do you know how to remove bacteria from drinking water?

Bacteria in your drinking water can make you sick, especially if you are susceptible to infection. Having clean, safe water is important for your health and peace of mind.

You may be surprised to learn that your drinking water might have bacteria in it, even if you have tap water. Fortunately, there are several ways to remove bacteria from your water including filtration, chemical disinfection, UV light, and reverse osmosis. Testing is the only way to know for sure if your water is contaminated. If you need to disinfect your water, look for equipment certified by NSF or other agencies to be confident it will complete remove the bacteria in your water.

In this article, you’ll learn about the different ways of removing bacteria from drinking water so that you can make sure your family has safe drinking water at all times!

Bacteria in Drinking Water – A Big Problem

Agricultural runoff contaminating water supply
Agricultural runoff is a common source of bacterial contamination in drinking water.

Clean water is one of the most important aspects to maintaining good health. Drinking water contaminated with bacteria can make you sick or potentially lead to more serious health issues over time.

Most people who drink bacteria-contaminated water experience mild symptoms such as nausea, vomiting, diarrhea and stomach cramps. However, in some cases there are dangerous diseases like dysentery, cholera and typhoid fever that are much more severe.

Public water supplies in the US are regulated by the Environmental Protection Agency (EPA). The EPA requires all public drinking water supplies to be disinfected and routinely tested to ensure adequate treatment. As a result, most tap water is free of bacteria and other pathogens.

People who don’t have access to public water supplies must get their water from wells, springs, rivers, and lakes. These private drinking water systems are not regulated by the EPA. Homeowners are responsible for ensuring their water is safe to drink. Unfortunately, most bacteria problems in drinking water occur with these private drinking water supplies.

Bacteria and pathogens that cause illness

There are many microorganisms that can cause illness if present in drinking water. Some common bacteria that can cause illness include:

  • E. coli
  • Salmonella
  • Campylobacter

In addition to bacteria, your drinking water may also be contaminated with viruses or protozoa. Common pathogens include:

  • Enterovirus
  • Hepatitis A
  • Norovirus
  • Rotavirus
  • Cryptosporidium (protozoa)
  • Giardia intestinalis (protozoa)

These pathogens are found in both human and animal feces. Drinking water can become contaminated by improperly maintained septic systems, backflow of contaminated water into plumbing lines, inadequate disinfection, and agricultural runoff.

Not all bacteria cause disease or illness – sulfate reducing bacteria can produce hydrogen sulfide which makes your water smell like rotten eggs.

Presence of bacteria in well water

People who get their drinking water from a private well need to pay special attention to the water quality. Wells can become contaminated with bacteria and other microorganisms from several sources.

One common source of bacteria in well water is surface runoff. When it rains, the soil becomes saturated and any contaminants on the surface (such as animal feces or pesticides) can leach into the groundwater.

Another common source of bacteria in well water is septic systems. If the system is not properly maintained, bacteria and other pathogens can contaminate the well water.

Bacteria in rivers, lakes, and streams

Some homes get their drinking water directly from surface water sources such as rivers, lakes, and streams. These surface water bodies can be contaminated with bacteria from many different places such as human sewage, wildlife, or agricultural runoff.

If your water comes from one of these sources, it’s important to take precautions to protect yourself and your family from bacteria. This includes testing the water routinely and using a treatment method to remove pathogens.

Bacteria and public water supplies

Just because you drink tap water doesn’t mean you’re safe from bacteria. In fact, tap water can contain a wide variety of bacteria including E. coli, Giardia lamblia, and Legionella pneumophila. These bacteria can cause mild to severe illness depending on the person and the type of bacteria.

The first thing you should know is how common it is for tap water to have some level of contamination by bacteria. According To the Center for Disease Control and Prevention (CDC), about 23% of people who receive water from a community water system in the United States get their drinking water from a source that violated health-based standards.

The CDC also states: “More than half of violations were due to not having enough disinfectant.” This is significant because inadequate levels of chlorine or other disinfectants in your tap water may result in disease causing bacteria in your tap water.

Fortunately, bacterial contamination of public water supplies is not that common. In the rare instances that it occurs, the utility is required to conduct testing and they can warn consumers about the problem.

Treatment Methods to Remove Bacteria from Your Drinking Waterreverse osmosis filter for bacteria removal

Bacteria in your drinking water represents a significant risk to your health and well-being. There are several methods that can be used to remove bacteria from your drinking water. The most common treatment methods are:

  1. filtration
  2. chemical disinfection
  3. UV disinfection
  4. ozonation
  5. distillation
  6. reverse osmosis
  7. boiling

Each of these treatments has its own advantages and disadvantages. In many situations, you should consider using two or more methods to ensure you adequately destroy the bacteria and have a safe, reliable water supply.

Let’s take a closer look at each of these treatment methods.

1. Water filters to remove bacteria from drinking water

Water filters can be used to remove bacteria from drinking water. It is important to note that not all filters are suitable for removing bacteria. You need to use a filter that is certified to remove bacteria.

The pore size, also referred to as the micron rating, is a measure of the particle that the filter can remove. The smaller the pore size, the more effective the filter will be at removing particles such as bacteria.

Most bacteria are about 5 to 10 microns long and 1 to 2 microns in diameter. A filter must have a pore size that is smaller than the diameter of a bacteria – or 1 micron.

In addition to bacteria, you may also have protozoa or viruses in your water.

Protozoa are less than 50 microns in size. Cryptosporidium are 4.2 to 5.4 microns; Giardia intestinalis are 9 to 20 microns.

Viruses range in size from 0.005 to 0.3 microns.

Given the serious health risks of drinking water with bacteria, you want to select a filter with a pore size that is much smaller than 1 micron. This gives you a factor of safety to ensure no bacteria can get through. Remember, bacteria are living organisms that reproduce – it only takes one to contaminate your drinking water!

ultrafiltration: these filters have a pore size of 0.01 microns. Ultrafiltration can remove bacteria and protozoa from drinking water. Ultrafilters are not suitable to remove viruses from drinking water.

nanofiltration: nanofilters have a pore size of 0.001 microns. Nanofiltration can remove bacteria and protozoa from drinking water. Nanofilters can be used to remove viruses from drinking water.

Before purchasing a filter to remove bacteria or other pathogens, look for the NSF 53 or 58 rating.

If you are using a filter to remove viruses, you may need to also use a chemical disinfectant to ensure adequate removal.

2. Chemical disinfection to remove bacteria from drinking water

Chemical disinfection is a very effective method for removing bacteria from drinking water. Disinfection also works well for viruses and protozoa.

Chemicals used for disinfection include:

  1. chlorine
  2. chloramine
  3. ozone

Chlorine is the most common disinfectant used in water treatment plants. The main form of chlorine used is sodium hypochlorite, which is a liquid.

Chlorine reacts with organic matter in the water to form disinfection byproducts (DBPs). Some of these DBPs are carcinogenic and can be harmful to your health. Chlorine also has a strong taste and smell.

Chloramine is another widely used disinfectant. Chloramine is formed when ammonia is added to chlorine. It is very effective at killing bacteria, viruses and protozoa.

Many public water supplies use chloramine because it lasts longer and is less corrosive than chlorine. Chloramine also has a strong taste and smell.

Ozone gas is a very powerful oxidant that is is formed when oxygen atoms combine. Ozone can be used to remove bacteria, viruses and protozoa from drinking water. It is more effective than chlorine or chloramine at killing pathogens without creating DBPs that pose health risks.

Ozone has a very short half-life, so it does not create the unpleasant taste or smell that chlorine and chloramine do. However, ozone isn’t suitable for removing

Cryptosporidium and some Giardia are not destroyed by chlorine.

While chemical disinfection is very effective at removing bacteria and other pathogens from drinking water, it is not a treatment method that can used in a residential setting. This is because the chemicals used are dangerous and difficult to handle. In addition, the dosing of disinfectant is very critical to how well the bacteria are killed. Too little, and your water isn’t adequately disinfected. Too much, and your water tastes bad and may not be safe to use.

3. Ultraviolet light disinfection for removing bacteria from drinking water

Ultraviolet (UV) light is a very effective disinfectant. It can remove bacteria, viruses, and protozoa from drinking water. UV light is used in both residential water treatment as well as water treatment plants for disinfection.

The UV lamps produce ultraviolet radiation of short wavelengths, typically between 120 and 400 nanometers (nm). The most effective UV wavelength to kill bacteria ranges from 185 to 254 nm.

UV light attacks bacteria by damaging their DNA.

UV disinfection requires clear water to allow the light to reach all bacteria and pathogens. Turbidity and color must be removed by filtration or other means to ensure adequate disinfection. For this reason, UV light disinfection always includes pre-filtration.

UV light units are also used with other treatment methods, such as filtration and reverse osmosis, as a second line of defense. The UV disinfection destroys and pathogens that make it past the filter or RO unit to ensure you have safe drinking water.

4. Ozonation to remove bacteria from drinking water

Ozonation is a disinfection process that is very effective for removing bacteria, viruses, and protozoa from drinking water. It involves generating ozone gas and dissolving it into the water using a venturi or bubbling tank. The ozone reacts with and destroys the pathogens and other contaminants present in the water.

Ozone is a very toxic gas and requires monitoring and specially built equipment for water treatment. Due to the complexity and dangers associated with ozone, it is not typically used in residential settings.

5. Distillation to remove bacteria from drinking water

Countertop water distiller
Distillation is very effective at removing bacteria and other pathogens from drinking water.

Distillation is very effective at removing bacteria in drinking water. Distillation also removes viruses, protozoa, and other microorganisms from water.

Distillation treatment involves boiling water until it becomes steam. The steam is then condensed and collected.

You can purchase a countertop distillation unit that produces enough water for drinking and cooking. You can also use a whole-house distillation system that can provide enough water for our entire home.

Distillation is very expensive. The equipment is expensive to purchase and install. This process also uses a lot of energy to boil the water and condense it.

6. Reverse osmosis to remove bacteria from drinking water

Reverse osmosis filters can remove bacteria from drinking water very effectively. RO systems can also remove viruses and protozoa from drinking.

Read my article on using reverse osmosis treatment to remove bacteria from drinking water.

RO filters work by passing water through a membrane with very tiny holes. The microbes and other contaminants are too large to pass through the pores in the membrane while pure water passes freely.

Most RO systems remove 99.9+% of all bacteria, viruses, and protozoa from drinking water. Because bacteria are living organisms, it only takes one to result in contaminated water downstream in your holding tank or plumbing.

Not all reverse osmosis systems are rated for bacteria. Check for NSF 53 or 58 certification so you know it is intended to be used for removing bacteria.

Most RO systems used for removing bacteria, viruses, or cysts include a UV light disinfection module on the discharge. The UV system provides a second layer of treatment to destroy any bacteria or other pathogens that make it through the RO filter.

7. Boiling water to remove bacteria

Boiling is a very effective method to remove bacteria from drinking water. Boiling also removes viruses, protozoa, cysts, and other pathogens from drinking water.

To adequately disinfect your water, you need to bring it to a rolling boil for at least 1 minute. If the water is cloudy, let it sit for the particles to settle out. Filter the water to remove the turbidity.

Boiling is an emergency, or temporary, treatment for bacteria. You can’t rely on boiling as a permanent solution to protect yourself and your family from bacteria or viruses.

Bacteria Filter Configurations

There are several types of water filter configurations available, including:

point-of-use (POU) filters: a POU filter treats water at your sink or faucet.

whole-house filters: whole-house filters, also known as point-of-entry (POE) systems, are installed on the incoming water line and treat all the water that enters your home.

under-sink filters: these filters fit under your sink and provide filtered water to a single faucet.

countertop filters: countertop filters sit on your kitchen counter and provide filtered water for drinking and cooking.

You can select the type of filter that best serves your needs and fits into your home.

Emergency Disinfection Methods to Remove Bacteria from Drinking Water

In emergencies, such as a flood or disinfection problem with the public water supply, you may have to disinfect your drinking water. There are several methods you can use to disinfect water in an emergency:

  1. chlorine bleach: add unscented chlorine bleach at a rate of one gallon per 1000 gallons of water. Stir well and let stand for 30 minutes.
  2. iodine tablets: these tablets release iodine into the water, which kills bacteria and other microorganisms. One tablet treats one quart of water.
  3. solar disinfection: also known as SODIS, this method uses sunlight to kill pathogens in the water. Using a clear plastic bottle filled with untreated water, place it on top of a reflective surface and leave it in direct sunlight for at least six hours. A few days later when you open the bottle, be sure to thoroughly clean the cap and mouth with soap and water.
  4. boiling: boiling water is a simple and very effective method to disinfect your water. Bring the water to a rolling boil for one minute.

How to Know if Bacteria Are in Your Drinking Water

Coliform bacteria test
Coliform tests are the only way to know for sure if your water contains bacteria.

It is critical to know if your water contains any bacteria. Unfortunately, you can’t tell if your water is contaminated by its appearance or smell. The only way to know for sure is to have a laboratory test it.

If you have a private well, you should test it once per year for coliform. The best time to sample the well is late spring or early summer.

There are several laboratory methods that are used to determine if your drinking water contains harmful bacteria.

Total coliform: this is a quick and inexpensive test that lets you know if there are bacteria in your drinking water. This test does not differentiate between disease causing bacteria and harmless bacteria.

Fecal coliform: this test identifies the presence fecal coliform which indicates your well has contaminated by animal or human feces. A positive result means your well is contaminated and requires immediate disinfection and treatment.

E. coli: E. coli is the most common species of fecal coliform group and is said to be the fecal coliform bacteria that best indicates fecal pollution and potential pathogens.

Certified Equipment for Removing Bacteria and Viruses from Drinking Water

If you are installing treatment equipment to remove bacteria and other pathogens from your drinking water, you should look for third-party certification. NSF and ANSI are two independent organizations that test water treatment equipment and develop standards to ensure it provides the level of protection promised by the manufacturer.

Here are important NSF standards that are applicable to removing bacteria from drinking water.

  • NSF Standard 53: Targets specific health effects such as cryptosporidium and giardia
  • NSF Standard 58: Specific to reverse osmosis filters
  • NSF Standard P231: Deals with microbiological filtration


Removing bacteria from drinking water is important to protect your health. Your water can have bacteria in it, even tap water that comes out of the faucet. In this article, we reviewed several ways you can remove the bacteria – filtration, chemical disinfection, UV light disinfection, reverse osmosis, and distillation. We also covered emergency options if continuous treatment isn’t available – boiling, bleach, and purification tablets.

I hope this article gave you a good understanding of bacteria in water and the different ways to remove it. Good luck with removing harmful bacteria from your water!

Boch Richard

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children.

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