Does Reverse Osmosis Remove Cryptosporidium from Water?
Written by: Gene Fitzgerald // Last Updated: Apr 13, 2023
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The chlorination of water supplies has protected us for a long time from waterborne illness.
Unfortunately, there are some nasty bugs that chlorination is unable to deal with. One of those is cryptosporidium, a cyst that can cause severe gastrointestinal illness.
If you are worried about crypto being present in your water supply, you may wonder if reverse osmosis is a good solution to remove it. Let’s find out.
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Key Takeaways
- Reverse osmosis effectively filters cryptosporidium from water; however, most reverse osmosis systems have been designed for biologically-safe water.
- If the level of cryptosporidium in your water is very high, you may want to consider UV disinfection as an alternative.
Does Reverse Osmosis Remove Cryptosporidium from Water?
So, does reverse osmosis remove cryptosporidium from water?
Yes, reverse osmosis removes cryptosporidium from water very effectively. In fact, it can remove any kind of protozoa from water, including giardia, as well as most bacteria and viruses also.
This is due to its very fine membrane pore size of 0.0001 microns, which is even smaller than nanofiltration.
How Effective Is Reverse Osmosis in Removing Crypto?
Reverse osmosis should remove all cryptosporidium from water, provided the system has been adequately maintained and used.
How Does Reverse Osmosis Water Purification Remove Cryptosporidium?
Reverse osmosis removes cryptosporidium from the water via size exclusion. Simply put, crypto is too large to fit through the tiny pores of a reverse osmosis membrane. Reverse osmosis membrane pores are 0.0001 microns, whereas the average cryptosporidium is 4-6 microns.
It is important to note, though, that most reverse osmosis systems for home use are designed for use with biologically-safe water, not biologically-unsafe water. If your water has a high enough level of cryptosporidium to be considered biologically hazardous, this can accumulate on the reverse osmosis membrane and eventually make it into your drinking water. In this case, UV disinfection would be a good step to add to your RO system.
Other Ways to Remove Cryptosporidium from Water
There are several other methods you can use to remove cryptosporidium from your water supply aside from reverse osmosis.
UV Disinfection
UV disinfection is the recommended method for dealing with cryptosporidium levels in drinking water. While it does not technically remove the protozoa, it does scramble its DNA and inactivates it, making crypto incapable of spreading disease.
Boiling/Distillation
Boiling and water distillation is another method of killing cryptosporidium; however, it can be challenging to maintain if you use a lot of water, as you have to consider the time it takes to boil or distill, and cool water for drinking.
Any Mechanical Filtration with 1 Micron Max Absolute Pore Size
Any filtration method with a maximum absolute micron rating of 1 will be good enough to filter crypto as it is 4 to 6 microns in size. However, you will run into the same issue if your water is heavily contaminated as you would with RO filtration.
How About Shock Chlorination?
Unfortunately, cryptosporidium is a chlorine-resistant organism and may not be treated by shock chlorination, which is why it is so concerning.
Watch Out for NSF Standard 53/58 Certifications for Crypto Removal
If you are concerned about cryptosporidium in your drinking water and you want to install a reverse osmosis system to make sure it is all dealt with, you need to keep an eye out for specific NSF certifications when you purchase.
NSF standard 58 is for RO systems specifically, and NSF standard 53 is for all water filtration types. Both can indicate that a reverse osmosis system can filter crypto. Still, you need to check for cryptosporidium reduction rates specifically.
What Is Cryptosporidium?
Cryptosporidium is a parasite that is resistant to chlorine and can affect both humans and animals. It is found in freshwater, saltwater, soil, food, and even swimming pools. Once ingested, it can pass through the stomach and into the small intestine, where it can live for months, causing infection.
Symptoms of infection include diarrhea, vomiting, and weight loss. If left untreated, it can cause long-term health problems like dehydration and malnutrition.
Protozoan Cysts
Protozoan cysts are the infectious particles of protozoa. The cysts have a hard protein shell which makes killing them all the more difficult (hence their resistance to chlorine). Types of protozoan cysts include cryptosporidium, giardia, toxoplasma gondii, and entamoeba. Cryptosporidium is most commonly associated with waterborne disease outbreaks in the USA.
When consumed, these cysts will hatch in the intestinal tract and reproduce, causing illness. In the elderly and children, complications from this can be fatal.
Further Reading:
How Does Crypto Enter Our Water Systems?
While most cryptosporidium infections are due to poor hygiene practices, it has been known to cause illness even from municipal water supplies. It can enter water supplies by contamination from animal or human waste, agricultural runoff, or through recreational water activities.
Once in the water supply, cryptosporidium is extremely hard to get rid of without using specialized filtration or disinfection methods, namely reverse osmosis and UV water purification.
Health Effects
The health effects of cryptosporidium include:
- Diarrhea
- Stomach cramps
- Nausea and vomiting
- Fever
Symptoms usually appear 14 days or so after exposure and can last several weeks. Treatment is with antibiotics, though prevention is always the more effective method.
A Safe Level in Drinking Water?
There is no established safe level of this parasite in drinking water, though the WHO recommends that it be below one oocyst per 10 liters of water.
How to Test Water for Cysts
If you are worried about cryptosporidium or other cysts in your drinking water, you can test it at home using a test kit, which is then sent to a laboratory for analysis.
If you have any thoughts about the question, does RO remove cryptosporidium, please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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