Cysts, Parasites & Protozoa: What’s the difference?
Depending on where you look – on our website or on others – the terms ‘cysts’, ‘parasites’, and ‘protozoa’ come up regularly as something that can be removed by water filters and purifiers. But what is the difference between them? And if a purifier only mentions ‘cysts’ does that mean it won’t remove parasites or protozoa?
The good news is that if a filter or purifier mentions one, it will cover all of them. Here’s why:
Parasites
This is the broad term for any organism that lives on or inside another organism (the host) and benefits at the host’s expense. It’s a very general term that covers everything from mistletoe to fleas, ticks, and tapeworms to the microscopic kind that are found in food or water.
Protozoa
These are single-celled, microscopic organisms. Many protozoa are a type of parasite, but not all of them. They are responsible for diseases like Giardia (found in water) and malaria (found in blood).
Cysts
A cyst isn’t a type of organism; it’s a ‘life-stage’. If protozoa are in harsh conditions, they create a protective shell around themselves and stay that way until they get to somewhere they can thrive (ie, get consumed by a host). At that point, they come out of their shells and start reproducing.
How can they be removed from water?
The typical size of waterborne protozoa and cysts is between 5 and 50 microns (at least 250 times bigger than viruses), so any filtration purifier with a pore size less than 5 microns will safely remove parasites (including protozoa and cysts).
LifeSaver ultrafiltration purifiers are designed to remove viruses and bacteria too, so they have a pore size of around 0.015 microns. Compared to the sizes of bacteria and parasites, the pores are tiny.
Boiling your water will kill all these organisms (although they’ll still be in the water), as will using purification tablets. UV purification will probably kill all of them, but remember that smaller organisms can hide behind the larger ones, so they may not get zapped. And you’ll need spare batteries.
When choosing a portable water purification method, always do your research as to what might be present in the area; there are other types of contaminants that may be present, like chemicals and heavy metals. These can be reduced by adding an activated carbon filter or by opting for a Graphene:Ultra Jerrycan. And look carefully at the claims being made by filter manufacturers and the certification behind them. Check for evidence that NSF P231 is met as an absolute minimum.
If you want to know more, check out Paul Kirtley’s article ‘Water Contamination: The 5 Contaminants You Need to Know About’. He also concludes that a two-pronged approach might be required, although he hasn’t yet explored the ultrafiltration/activated carbon combo as a solution that includes virus removal. A LifeSaver water purifier will be sufficient to make any water microbiologically safe to drink, and it deals with the turbidity he talks about by removing sediment, dirt, and organic matter.
Still curious? Take a look at some of our other blogs:
Who Makes the Best Portable Water Purifiers?
The Water Might Look Clean But…
Don’t Just Filter. Purify.