How to Remove Viruses from Drinking Water

Posted by
John Woodard on June 09, 2023
Waterborne viruses afflict millions of people each year who consume contaminated water, and, according to the World Health Organization, at least two billion people use a contaminated drinking water source. As the global population increases and safe drinking water becomes scarcer, knowledge of waterborne viruses and other waterborne diseases will grow in importance. Below you will learn about waterborne viruses, how to know if your water is contaminated, how to remove viruses from water, and how to safeguard your water supply.

How do viruses get into water?

Viruses get into water when water is contaminated by the urine or feces of an infected human or animal. An improperly working sewage system, polluted stormwater runoff, and floods heighten the risk. Well water and water from unsterilized sources, such as lakes and rivers, are especially vulnerable to contamination. In fact, all untreated water sources are at risk of viral contamination, and many developing nations suffer from viral outbreaks because of a lack of access to clean water.

However, even a municipal water source is not without risk. In the event of a flood or natural disaster, municipal disinfection processes could fail and leave your water supply susceptible to viruses and other dangerous pathogens. If the disinfection process fails, your water company will send out a boil water advisory, because they cannot guarantee the safety of your water supply.

How do you test for viruses in water?

The most accurate way to test for viruses in water is to send a water sample to a lab. In the lab, the water is concentrated into a smaller volume. Then, virus detection is achieved through nucleic acid extraction or molecular detection, such as polymerase chain reaction (PCR) tests. If you are interested in having your water tested for viruses, contact a certified laboratory in your state.

Although there are currently no home water test kits that detect viruses, a home coliform bacteria test can indicate if your water contains disease-causing organisms and alert you if further testing is required. Coliform bacteria are present in the feces of humans and animals. While they don’t usually cause illness, their presence signals that other pathogens, such as bacteria, viruses, and parasites, may be present.

Municipal water providers test their water regularly, but, if you have a well, it is your responsibility to test for contaminants and to ensure your water supply is safe. Given that wells are especially vulnerable to contaminants after heavy rain and flooding, vigilant water testing is highly recommended. Testing aside, any untreated water source is at risk of viral contamination, so it is advised to always take precautionary measures (e.g., install a water treatment system) to protect your home and family from illness.

Learn More: How to Remove Bacteria from Drinking Water

Types of waterborne diseases

Hepatitis, Norovirus, Rotavirus, Cryptosporidiosis, and Giardiasis are the most common waterborne viruses worldwide. They can be spread by drinking, bathing, washing, or eating food exposed to contaminated water.


There are five different types of viral Hepatitis (A, B, C, D, and E) and all cause inflammation of the liver. However, Hepatitis A and E are the only two that spread through contaminated water. Symptoms of both Hepatitis A and E include fever, weakness, loss of appetite, nausea, and jaundice. The good news is that most patients fully recover and have no long-term side effects, but good hygiene, handwashing, and avoiding drinking tap water while abroad are good practices to avoid getting sick. Both children and adults also have access to a Hepatitis A vaccine.


Norovirus is a virus that spreads rapidly and easily, as it only takes a small amount of virus particles to make a person sick. Common symptoms include diarrhea, vomiting, nausea, and stomach pain. Norovirus, along with all waterborne pathogens, are tricky because they can spread beyond drinking water. If food is grown or harvested with contaminated water, you can also get sick. For example, oysters may be harvested, and fruits and vegetables may be irrigated with contaminated water. To prevent Norovirus, it is recommended to wash your hands often, rinse fruits and vegetables before eating, thoroughly cook shellfish, and avoid drinking water that may be contaminated.


Rotavirus is most common in infants and young children and causes vomiting, diarrhea, loss of appetite, and may lead to dehydration. Adults can also get Rotavirus, but usually have milder symptoms. There are currently two Rotavirus vaccines licensed for infants, but there is no vaccine for older children or adults. Hand washing, good hygiene, and avoiding potentially contaminated food and water aid in preventing the spread of Rotavirus.


Cryptosporidiosis is a disease caused by the parasite species known as Cryptosporidium, commonly abbreviated as Crypto. Common symptoms of Cryptosporidiosis include vomiting, diarrhea, stomach cramps, weight loss, and fever. While Crypto are not viruses, they are the leading cause of waterborne disease in the United States. They contaminate water sources through fecal matter of infected people or animals. While humans can be infected by some types of Cryptosporidium, animals are susceptible to more. Like viruses, Crypto can be killed with UV purification, ozone water treatment, and boiling water. It can also be removed from water via distillation and ultrafiltration. Chlorine does not kill Cryptosporidium, so another treatment method must be used to eliminate the parasite from susceptible water sources.


Like Cryptosporidiosis, Giardiasis is a disease that results from a parasite, not a virus, but it is one of the most common waterborne diseases. Giardiasis is caused by the parasite Giardia, which contaminates water through the stool of infected people or animals. Symptoms of Giardiasis include diarrhea, stomach cramps, fever, hives, itchy skin, and swelling of the joints. Unlike Cryptosporidium, Giardia can be killed by chlorine water treatment. It can also be killed or removed from water by UV purification, ozone water treatment, distillation, ultrafiltration, and boiling.


How to kill viruses in water

Viruses can be removed from water through ultraviolet purification, chlorine, ozone water treatment, distillation, ultrafiltration, and boiling water.

1. Boiling Water

The simplest way to kill viruses in water is to boil the contaminated water for at least one minute. If your elevation is higher than 6500 feet, boil the water for at least three minutes. Before storing or drinking the water, allow it to cool. If you are storing the water for later use, ensure the container is tightly sealed. Improperly storing your boiled water can lead to further contamination.

2. Ultraviolet purification

Ultraviolet purification systems utilize UV light to damage the DNA of viruses and other living organisms, rendering them unable to reproduce and unable to spread disease in the water supply. However, ultraviolet purification systems are most effective when water is pre-treated by a different filter, such as a sediment filter, because dirt and debris shield microscopic viruses, bacteria, etc. from UV light. When water is pre-filtered, ultraviolet purification systems can neutralize 99.9% of living organisms.

Learn More: What is a UV Water Purifier and How Does It Work? | What is a Sediment Filter and How Does It Work? 

3. Chlorine

Chlorine eliminates viruses and other pathogens from water through a chemical reaction. When chlorine is added to water, it forms a weak acid called hypochlorous acid that penetrates the cell walls of viruses and bacteria, destroying them from the inside out. Chlorine is a popular choice at water treatment centers around the world because it continues to keep water clean overtime. However, it may leave a residual chemical smell in your tap water. If this is a problem you encounter, an activated carbon filter is recommended to greatly improve your water’s taste and smell.

Note that chlorine cannot destroy the parasites in the species Cryptosporidium. To eliminate the risk of Cryptosporidium in water, use a different treatment method, such as UV purification, ozone water treatment, distillation, ultrafiltration, or boiling.

Learn More: Activated Carbon Filters 101

4. Ozone water treatment

Ozone water treatment removes viruses and other troublesome contaminants from water through oxidation. Ozone (O3) is an oxygen compound and one of nature’s most powerful oxidizers. In ozone water treatment, ozone is first created in an ozone generator. Then, it is injected into water where it oxidizes organic material in the membranes of viruses, bacteria, and parasites. This weakens, ruptures, and kills their cells. Ozone water treatment not only eliminates viruses and other dangerous pathogens, but it is also incredibly fast and purifies water in a matter of seconds.

Learn More: What is Ozone Water Treatment and How Does It Work?

5. Water distillers

Water distillers eliminate viruses through distillation. Distillation is a process that mimics how water is purified in nature: through evaporation in the atmosphere. Water distillers convert water into steam, eliminating viruses and other contaminants because they cannot evaporate as water can. Once the water returns to its liquid form, it is contaminant free.

Learn More: What is a Water Distiller and How Does It Work? | What is Distilled Water and Is It Safe to Drink?

6. Ultrafiltration

An ultrafiltration system uses standard home water pressure to force water through a hollow fiber membrane that traps viruses, bacteria, chlorine, algae, and metals. Only clean water and minerals pass through. Viruses are too small to be stopped by most filters, but an ultrafiltration membrane is about 0.025 microns, while viruses are about 0.1 microns. To put their miniscule size in perspective, the average human hair is 70 microns wide! However, ultrafiltration should not be relied on to treat water from natural sources, such as a lake or rainwater. An ultrafiltration system works best in tandem with other precautionary measures, like a UV system.

Learn More: What is Ultrafiltration?

Does boiling water kill viruses and bacteria?

Yes, boiling water kills viruses and bacteria. The proper method is to bring your water to a rolling boil for one minute, or if you are at an elevation of 6,500 feet or higher, boil your water for three minutes. In the event of a boil water advisory or if you need to drink water from an unsterilized source, such as a stream while camping, boiling your water will inactivate viruses, bacteria, parasites, and other dangerous pathogens.

Learn More: Boil Water Advisory Procedures


Boiling water

Do water filters remove viruses?

Water filters do not effectively remove viruses. Viruses are too small to be ensnared by filters, with the exception of ultrafiltration. However, even ultrafiltration should be used in conjunction with another water treatment system.

Does COVID-19 spread through water?

No, there is currently no indication that COVID-19 spreads through water. According to the Centers for Disease Control (CDC), there is no evidence that anyone has contracted COVID-19 through drinking water, recreational water, or wastewater. Instead, it is transmitted through air or surface contact.  



If you have any further questions or concerns about waterborne viruses or how to safeguard your water supply, please don’t hesitate to contact us.


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