Viruses in tap water

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States Affected
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People Affected
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Toxicity Rating
Health Effects

Gastrointestinal illness (such as diarrhea, vomiting, and cramps), hepatitis, meningitis

The legal limit is
Health Guideline
what is considered unhealthy
Legal Limit
0 virus particles per 100 milliliter sample of municipal water
What are viruses?
Viruses are tiny disease-causing organisms approximately 100 times smaller than bacteria. As a matter of fact, most are unable to be seen in an ordinary light microscope. They are highly contagious and many are transmitted by fecal-oral contact. In other words, they are shed via feces and urine, then spread by ingestion of contaminated particles in food, water, air, and other objects and surfaces.
Waterborne viruses can be found in contaminated water supplies that have not been treated properly. Infection is often associated with the stomach flu and related symptoms like diarrhea, cramping, fever, and vomiting. However, some waterborne viruses can cause severe illness including meningitis and hepatitis, as well as complications that can lead to death. Viruses have the frightening ability to cause outbreaks and antibiotics cannot cure viral infections.
How do viruses get into tap water?
Water becomes contaminated with viruses when it comes in contact with contaminated feces or urine from livestock, wildlife, and humans.
Sewage overflows, damaged or leaky sewage and septic systems, aging infrastructure, and runoff from snow, irrigation, and flooding can all lead to contamination of water systems and wells. Older treatment plants, rural water supplies and wells, and areas affected by heavy rainfall and snow are particularly susceptible to contamination.
While the U.S. EPA regulates tap water to help prevent viruses, water treatment is not a perfect science. Nor is regulation. There is no single treatment or method that can eradicate all waterborne viruses under all conditions, and there’s no guarantee that your tap water is always virus-free.
Why are viruses harmful?
The waterborne viruses the U.S. EPA regulates, known as enteric viruses, attack the gastrointestinal (GI) or respiratory tracts. Infections from these viruses are often associated with the stomach flu and related symptoms like diarrhea, fever, cramping, and vomiting. However, some waterborne viruses can cause severe illness including meningitis, hepatitis, polio, and more. The complications from infection can be more dangerous than the symptoms. In fact, some complications can lead to death.
Waterborne viruses tend to be most harmful to children, elderly, pregnant women, and people with weakened immune systems.
Which waterborne viruses are regulated?
The U.S. EPA regulates enteric viruses—human viruses primarily transmitted by the fecal-oral route—to help prevent them from contaminating public water supplies. The following viruses are considered enteric:
  • Noroviruses: Causes vomiting, diarrhea, and stomach pain. Dehydration is a possible but rare complication. Noroviruses may sound familiar due to recent outbreaks on cruise ships.
  • Hepatitis A: Causes liver infection. In rare cases, liver failure and death can occur.
  • Rotavirus: Causes diarrhea and vomiting in infants and children. Severe cases can lead to dehydration and death. Most U.S. infants receive rotavirus vaccinations.
  • Poliovirus: Causes polio. Due to vaccination, no case of polio has originated in the U.S. since 1979. However, outbreaks have occurred worldwide and the disease can be brought stateside by infected people.
  • Adenoviruses: Causes pink eye, tonsillitis, ear infections, and other upper respiratory tract issues.
  • Coxsackie A: Causes hand, foot, and mouth disease. Symptoms include sores, rashes, and fever. Severe cases can lead to meningitis.
  • Coxsackie B: Associated with fever, headache, sore throat, and stomach pain. Just like Coxsackie A, severe cases can lead to meningitis.
  • Echovirus: This family of viruses affects the gastrointestinal tract (GI). Though uncommon, severe cases can lead to meningitis.
Is any level of a virus safe in water?
No. The U.S. EPA requires 99.99% removal of viruses, with a Maximum Contaminant Level Goal (MCLG) of 0 virus particles per 100 milliliter sample of municipal water.
What about Coronavirus?
Coronavirus has not been detected in drinking water supplies, and the risk to water supplies is “low,” according to the U.S. EPA. It is believed that current water treatment practices would kill coronavirus should it enter U.S. tap water sources.
What can I do about viruses in my tap water?
Viruses are 100 times smaller than bacteria and most are unable to be seen in an ordinary light microscope. Given they are so small (and mobile), they can sneak into water supplies and slip by water filters undetected. Ultimately, landing in your glass even after treatment or filtration. Here’s how to remove viruses from your tap water:
  • Upgrade to a Clearly Filtered filtered water pitcher. Our pitcher’s filter is tested and proven to remove waterborne viruses. Plus, it removes 54x more dangerous contaminants than typical carbon filters.
  • Boil water for three minutes, store in a sealed container, and refrigerate. Note: Boiling water does not remove lead, nitrates, pesticides, and other common contaminants found in tap water.
  • Invest in a water purifier certified to remove viruses. If the purifier uses ultraviolet light (UV) to remove viruses, be sure both the light source is free of obstruction and the water is completely clear. If not, the technology will not work. The bottom line is UV purifiers can render viruses inert, but you will still be drinking the “inactivated” viruses. Clearly Filtered, on the other hand, removes viruses.
  • Important: Typical carbon and charcoal filters do not remove viruses from water.
How does Clearly Filtered do at Removing Viruses in tap water?
Clearly Filtered with
Affinity Filtration Technology Product
Water Pitcher Filter
Under-the-Sink FIlter
Water Bottle Filter
Refrigerator Filter
Viruses in tap water Removal

1. US EPA. National primary Drinking Water Regulations. Accessed April 1, 2021.

2. US EPA. Coronavirus and Drinking Water and Wastewater. Accessed April 1, 2021.

3. CDC. Effect of Chlorination on Inactivating Selected Pathogen April 1, 2021.

4. CDC. A Guide For Drinking Water Treatment and Sanitation for Backcountry & Travel Use Accessed April 1, 2021.

5. PLOS Pathogens. Waterborne Viruses: A Barrier to Safe Drinking Water. Accessed April 1, 2021.

6. Water Tech Online. Bacteria and Viruses Commonly Found In Drinking Water. Accessed April 1, 2021.