Does Reverse Osmosis Remove Parasites? Find Out Here!
Written by: Alexandra Uta // Last Updated: Apr 27, 2023
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Waterborne diseases may sound like something you get from swimming in contaminated creeks and rivers, but the reality is they could be passed to you through your drinking water.
Yes, even if your drinking water comes from a treated municipal water catchment. The CDC has estimated that waterborne pathogens are responsible for 7,000 deaths, 120,000 hospitalizations, and 7 million illnesses yearly.
One type of waterborne pathogen is parasites, and with those concerning statistics, you probably want to know what you can to protect your household from ingesting a waterborne parasite and might be considering a reverse osmosis system to ensure your drinking water is safe.
But does reverse osmosis even remove parasites? Let’s see.
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Key Takeaways
- Reverse osmosis effectively removes parasites from water (though it doesn’t kill them).
- However, it may encounter issues with water with a high concentration of parasites, as they may cause wear and tear to the RO membrane over time.
Does Reverse Osmosis Remove Parasites?
Does reverse osmosis remove parasites from water?
Yes, reverse osmosis does remove parasites of all shapes and sizes from water and it is highly effective doing so.
This is because parasites are much larger than the microscopic pores of a reverse osmosis membrane and cannot move through with the filtered water.
What Are Parasites?
A parasite is a potentially disease-causing organism that lives on or within a host (that’s you!). Three main categories of parasites are capable of causing disease in humans: Helminths, protozoa, and ectoparasites.
They can enter our bodies through contaminated food or water, which is why it is essential to understand how to effectively remove them from drinking water sources.
It may seem unlikely that your home drinking water could carry a parasite; however, exposure to parasites is one of the leading causes of death for children under the age of five in developing countries and are more common in the USA than people may realize.
One type of parasite are protozoa. Protozoa are often microscopic and unable to be seen in the water, so you are unable to visually inspect your drinking water to see if they are present. Some of the more common groups of protozoa include:
- Sarcodina, for example, entamoeba
- Mastigophora such as giardia and leishmania
- Ciliophora such as balantidium
- Sporozoa such as plasmodium and cryptosporidium
Some parasites that may be visible to the naked eye include:
- Flatworms (platyhelminths) which include flukes and tapeworms
- Thorny-headed worms, also known as acanthocephalins
- Roundworms, known as nematodes
- Ectoparasites
How Effective Is Reverse Osmosis in Removing Parasites?
The best way to ensure your drinking water is free of any parasites is to utilize water filtration. A reverse osmosis system is highly effective and will remove pretty much any and all parasites in your water.
Some RO systems are even third-party certified for parasite removal. Watch out for an NSF Standard 53 certification specifically for removing cysts when shopping!
How Does Reverse Osmosis Water Purification Remove Parasites?
Reverse osmosis removes parasites via size exclusion. This, in essence, means that the pores of the RO membrane filter are way too small for the parasites to fit through.
RO membranes have pores that are about 0.0001 microns in size, but even some of the smallest parasites, such as cryptosporidium, are 4-6 microns in size which is much larger.
In saying this, it is important to remember that RO systems were not designed for use with biologically unsafe water (i.e., water with very high levels of crypto etc.). This is because too many parasites could mean accumulation of them on the RO membrane, which may degrade it over time, allowing the pores to increase in size and the parasites to slip through into the clean water.
That’s why, if your feed water has high levels of parasites, then a UV water purifier to kill them may be a better option.
What Else Does a Reverse Osmosis System Remove?
The contaminants that a reverse osmosis system will remove make for a rather long list! But they include aluminum, arsenic, barium, cadmium, chloride, chromium 6, copper, cyanide, fluoride, iron, lead, manganese, mercury, nickel, nitrates, phosphate, selenium, sodium, sulfate, sulfite, zinc, radium, uranium, pesticides such as lindane and endrin, volatile organic compounds, sediment, water disinfectants and DBPs – you name it!
Unfortunately, reverse osmosis being highly effective, it also removes beneficial minerals from water such as calcium and magnesium, but these can easily be added back in with a remineralization post-filtration step.
Other Ways to Remove Parasites from Water
While reverse osmosis is effective, other methods exist to eliminate parasites in your water.
Boiling/Distillation
Boiling or distilling your water effectively kills any parasites that may have made it into your water supply. This is often the reason a boil water advisory may be announced.
While it is effective, it can be a bit tenuous when it comes to scale. Boiling small amounts of water and waiting for it to cool can be a slow process, especially in a large household, and distillation can take time.
Further Reading:
UV Disinfection
UV disinfection is another effective method of killing parasites in water. UV light scrambles the DNA of parasites and renders them harmless, as they can no longer replicate and cause disease.
UV disinfection may not work for certain parasites, though, such as some cryptosporidium and giardia, as they have thick cell walls that the UV light may not be able to penetrate in some of the low-powered systems.
Chlorination?
Chlorination has been used for years in municipal water supplies to kill bacteria, viruses, and parasites. Unfortunately, it doesn’t work for all types though. Some chlorine-resistant cysts will not be affected by chlorination, again, cryptosporidium and giardia being the main ones.
Submicron Filtration
Submicron filtration is another method of parasite removal, like reverse osmosis. As the pores on a submicron filter are smaller than the parasite, they will be stuck on the entry side of the filter and unable to pass.
Examples of submicron filtration include certain sediment filters, ultrafiltration membranes, and even some activated carbon filter blocks with an absolute pore size rating of 1 micron or less.
However, this filtration method has the same limitations as reverse osmosis; too many parasites in the water can cause build-up on the filter, which may damage it and render it ineffective over time.
If you have any thoughts about the question, does reverse osmosis remove parasites, please don’t hesitate to leave a comment below!
About the Author Alexandra Uta
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