Parasites in Drinking Water

Both Cryptosporidium and Giardia are common in natural surface waters (like rivers and lakes) and can survive for a long time in the environment. These parasites may be found in water, food, soil or surfaces that have been contaminated with the poop of infected humans or animals.

You may come in contact with Cryptosporidium or Giardia by:

• Swallowing water while swimming or playing in lakes, streams, rivers, springs, ponds, swimming pools, hot tubs, or splash pads contaminated with Giardia or Cryptosporidium.
• Eating food or drinking water or other liquids contaminated with Giardia or Cryptosporidium.
• Touching your mouth after touching contaminated surfaces or objects, such as diapers or bathroom handles.

• Do not drink or swim in water that might be contaminated. 
• Try to keep water out of your mouth while swimming.
• Wash your hands after swimming and before eating.
• Regularly check your drinking water system to make sure it is sealed. 
• Thoroughly wash all fruits and vegetables with clean water before eating.
• Minimize contact with all human and animal poop, and wash your hands immediately after you do.
• Do not touch your face or mouth after touching animals, and wash your hands as soon as possible after.

If you think you are having symptoms caused by parasites, first talk with your health care provider. Then follow these steps to make sure your drinking water system is safe.

Use a safe water source

If you are diagnosed with a parasite infection, switch to a known safe water source by:

• Filling food-safe containers with water from a known safe source, like the town library, town hall, fire department, school, church or town office.
• Buying bottled water. Find a list of bottled water systems with no detections of per- and polyfluoroalkyl substances (PFAS).
• Buying water from a bulk water hauler and fill up a water tank. Find a list of bulk water haulers or search the internet for "bulk water haulers Vermont."

Find out how parasites might be getting into your water supply

Dug wells, springs, and surface water sources are more susceptible to contamination than properly sealed drilled wells.

• Test your water for total coliform and E.coli bacteria. 
  • If your results show bacteria were "detected" then surface water has somehow leaked into your water system, which means parasites like Cryptosporidium and Giardia could also get into your water supply.
• Check for ways parasites could be getting into your water. 
  • Make sure all seals, caps, fittings, and other places surface water may enter your water system are sealed off. 
  • Watch this video to see how to fix common problems.
• Assume your drinking water source is contaminated if it has been exposed to animals or surface water runoff.

The Health Department Laboratory does not offer parasite testing in water, but testing may be available through other certified drinking water labs. Please note that specialized Cryptosporidium and Giardia tests are costly, require large water samples, and may not give reliable results. 

The Health Department recommends testing your water for bacteria and other common contaminants regularly. These results may indicate if your water system is susceptible to surface contamination. To order a Vermont Homeowner Testing Package or individual drinking water test kits, call the Health Department Laboratory at 802-338-4724. Learn more about testing your drinking water.

If you suspect your drinking water is contaminated with Cryptosporidium or Giardia, do not drink your water or use it for cooking, washing fruits and vegetables, brushing teeth, washing dishes, and making ice cubes, baby formula and concentrated juices. You can either:

• Find a known safe source of water (such as the town library, town hall, fire department, school, church or town office), or 
• Boil water for at least one minute before using it.

Unlike most bacteria, both Cryptosporidium and Giardia are resistant to chlorine disinfection. Chlorine alone is likely not enough to make sure the water is safe to drink. However, flushing and disinfecting your water supply can help resolve bacteria contamination after repairs have been made to the system.

Permanent treatment options for parasites include:

• A filtration system that meets NSF/ANSI Standard 53 and is 1 micron (absolute), and is approved for cyst removal. 1-micron filters can clog quickly if sediment is in your water and may require additional pre-filtration to let the filter last longer.
• An ultraviolet (UV) light treatment system that meets NSF Standard 55, along with any necessary pre-treatment to ensure effectiveness.
• A reverse osmosis system with an NSF/ANSI Standard 58 certification.

Note: It is important to properly maintain any treatment system and change any filters by following the manufacturer’s instructions. Learn more about drinking water treatment.
 

Funding is available to help you pay for water treatment or to fix your water system. Learn more about financial assistance programs and eligibility.