How to filter bacteria and parasites from water

April 09, 2024 4 min read

How to filter bacteria and parasites from water

From trail hiking to picnicking, being outdoors holds many benefits to your physical and mental health. Staying properly hydrated while outside, especially during warmer months and hotter geographiclocations. In doing so, it is important to ensure you are not consuming any unwelcome bacteria or parasites–whether they come from a nearby lake, or your faucet at home. 

What are common parasites and bacteria found in water?

There are two common parasites that can be found in your water, no matter the location. First, and more widely known, is a tiny parasite called Giardia lamblia (also known as Giardia.) Giardia can be passed from infected animal to person, or infected person to person, through fecal matter (1). Once this feces enters a water supply, it can infect others through consumption, or eating/drinking off of dishes washed in the contaminated water. 

The Giardia parasite can lead to an illness called giardiasis, or “beaver fever” in some parts. According to the CDC, giardiasis can cause “a variety of intestinal symptoms,” including diarrhea, gas, nausea, dehydration, and other unpleasant bodily functions (2). Giardiasis can last from a few days to a few months, but it can be easily treated by a healthcare provider. 

The second common parasite found in water is called Cryptosporidium, or “Crypto” for short. Like Giardia, Crypto is microscopic and can be found in even the clearest of groundwater sources. The symptoms for ingesting a Crypto parasite are similar to those of giardiasis, with the addition of fever and lasting longer (1). Currently, there is no treatment for Crypto, so it is all the more important to protect yourself from ingesting these–and other–parasites and bacteria found in water. 

How do parasites and bacteria get in water?

It can be understood that lakes, streams, and other groundwater sources are likely home to various bacteria and parasites. Animals can carry many diseases, and through their feces these bacteria enter the water. Rain can carry fecal matter or infected runoff into these water sources. In more rural states where wildlife is abundant, it is common for their water to be contaminated due to animal feces (3). 

Animal feces, however, is not the only way parasites and bacteria can enter a water supply. Old or leaking sewer systems, sewage overflows, agricultural runoff, and polluted rainwater runoff can all also carry these germs into your water supplies (4). Animal activity is not to blame in these cases, but the risk of contracting disease from contaminated water is still prevalent. Whether your water comes from a scenic lake, apartment sink, or private well, there is still a possibility of parasites and bacteria being present in the water. 

How to remove bacteria and parasites from water

There are several methods for removing bacteria and parasites from water, each with a varying level of success. Adding iodine or chlorine to water will kill Giardia, but Crypto will remain in the water. Boiling water is a much more effective tactic, and after three minutes of boiling, “you will kill any protozoa the water contains” (1). Boiling water is an effective tactic, but it takes supplies and energy. Iodine or chlorine tablets do not require equipment, but their effectiveness is not ideal. The most effective and energy-efficient tactic for removing bacteria and parasites from water is using a microfiltration filter. 

The CDC recommends using a microfiltration filter with a pore size of less than 1 micron to remove bacteria and parasites (5). Such tiny pores block out protozoa like Giardia and Crypto, as well as bacteria. Many compact microfilters boast pore sizes of less than 2 microns, but Crypto is still known to get through those pores. Seychelle, however, creates hollow fiber membrane straws with a pore size of less than 1 micron, guaranteeing 99.999% of dangerous waterborne contaminants are removed from your drinking water. 

The Wrap-Up

Contaminants like bacteria and parasites can be present in even the cleanest looking water sources. They can enter a water supply through animal/human feces, overflowing sewers, and contaminated runoff, and these contaminants can lead to a slew of digestive issues. To combat harmful microorganisms in a cost-effective, safe way, consider a Seychelle Hollow Fiber Straw. Not only are they compact, but they will remove 99.999% of parasites and bacteria for up to 1,320 gallons of water. For fresh, safe water every time, choose Seychelle. 

Frequently Asked Questions

Can parasites be filtered out of water?

Yes. Microfiltration filters can effectively filter parasites out of water. 

How do you filter bacteria from drinking water?

Bacteria like E.coli and Salmonella Typhi, as well as others, can be killed by boiling the water. Additionally, there are water filters specifically designed for filtering parasites and bacteria. 

What are the symptoms of parasites in drinking water?

Parasites in drinking water usually cause a series of digestive symptoms, including diarrhea, nausea, gas, and dehydration.


  1. Alaska Department of Fish and Game, 
  2. Centers for Disease Control and Prevention,
  3. Minnesota Department of Health,,get%20into%20our%20drinking%20water.
  4. Centers for Disease Control and Prevention, 
  5. Centers for Disease Control and Prevention,,coli)%3B