Can Water Filters Actually Remove Viruses?

When you’re in the middle of a long-term survival situation one of your top priorities will be sourcing clean and drinkable water.

Many preppers will try to ensure their access to water by utilizing a water filtration system, either in the form of a portable emergency filter or a larger countertop or even a whole house filter. These filters are as a rule incredibly efficient at removing contaminants from water, but can they remove everything?

Can water filters remove something as small as a virus?

Yes, water filters can remove viruses so long as it’s capable of filtering out particles as small as 1/10,000th of a micron.

Not all filters are up to this lofty task, but so long as you verify your filter’s specs, you can be assured that your water will be free of viruses.

Removing soil and other impurities that make water cloudy is definitely important, and so is removing bacteria which are often the cause of various ailments but failing to remove viruses could wind up being a death sentence, as many serious diseases result from viral infection, specifically viruses that can be transmitted via contaminated water.

Below we will share with you additional information that will help you ensure your water filter is capable of this vital task.

How Does a Water Filter Work?

A water filter works by passing water, either through the force of gravity or pressure, through a material which has openings in it that will allow the water to pass while catching and holding various contaminants of a certain size.

The efficiency of a water filtration device is entirely dependent upon how many filters it uses, and what size contaminants they can remove from the water passing through them.

As you might imagine, for a water filter to perform well enough that we can stake our health on it, it will need to use a succession of filters each with increasingly small, fine openings.

This allows the water to pass through in an orderly, logical progression with the early stage filters removing large debris or comparatively large debris and the later stages filtering out tinier and tinier silt, sediment and germs.

Filter design and arrangement is actually critically important for proper operation of your water filter device, as throwing obviously dirty, foul water into a filter that is only designed for removing the finest contaminants will quickly overwhelm the filters and render it useless.

Conversely using a large, coarse filter alone might remove leaves, sticks, bug corpses and the like but will let every type and variety of bacteria, virus and other microorganisms through with no impediment.

What are We Up Against?

To defeat your enemy, you must first seek to understand it. Viruses are microscopic organisms, but they are so small, so unbelievably tiny, and are possessed of biology so strange that calling them organisms at all might actually be a stretch of our scientific understanding.

Viruses generally cannot live, or at least live in the sense of how a virus exists, outside of a host. Specifically, viruses live and reproduce by invading host entities at the cellular level, hijacking and dominating the components of the cell and bending them towards the purpose of reproducing the virus itself.

The newly xeroxed clones of the viral cell then burst forth to invade and dominate other cells, thus repeating the proliferation cycle.

Viruses are known for unstable and erratic mutation, but more germane to our concerns is the size of the average virus.

Though their size, at their scale, varies considerably they are only ever unbelievably, mind-bendingly small to us: viruses measure anywhere from a single tenth of a micron all the way to a single 10,000th of a micron in size.

Remind yourself that a micron is only a thousandth of a millimeter, and you’ll have some idea of just how small we are talking about here!

Beyond their unnerving method of reproduction and invisibly small size the impact that viruses have on their hosts is equally varied, and can run the gamut from simply making you feel run down and traditionally “ill” to outright killing you, and everything in between.

For this reason, it is imperative that you take no chances when it comes to removing viruses from a water source you plan on drinking.

What Kind of Filter Do We Need?

It isn’t always easy to determine what kind of water filter possesses filtration technology adequate to the task of removing viruses. What complicates matters is that this subject is constantly beset by corporate marketing speak, overhyped claims, and outright falsehoods when it comes to capability.

In general, you are always better off looking for a water filter that has an excellent reputation and is backed up by laboratory testing and, if applicable, certification.

Some water filters made by recognizable companies promise the world, and might indeed deliver excellent performance but only over a short period of time or in ideal conditions. You won’t have the benefit of either in the middle of a major survival situation.

To better understand what a given filter or filter package can deliver we should look to its rating. The most common filtration ratings, in increasing order of performance, are microfiltration, ultrafiltration and nanofiltration. That’s a lot of consonants! What do they all mean?

Without delving too far into the nitty gritty of the science microfiltration implies that a filter will halt the passage of any contaminant that is 0.1 micron in size or larger.

This is certainly impressive when it comes to filtering out inorganic debris but is not quite up to the task of catching the smallest water soluble contaminants, the majority of bacteria and any virus.

Our next stop is ultrafiltration, denoted when a filter will reliably halt contaminants that are 0.01 micron in size or larger. Contaminants in this size category are drastically smaller yet, and filters that can deliver this capability over time are not entirely commonplace.

These filters will do the job for virtually all inorganic water soluble contaminants, most bacteria and even a few viruses. Still, this is not a 100% certain level of performance when it comes to stopping viral contamination.

Last, and most impressive, is nanofiltration, denoting a filter that will halt any contaminant 0.001 microns in size or larger. When it comes to stopping viruses, this is the watermark, pardon the pun.

Virtually all known microorganisms and other contaminants will be stopped by a filter that attains this performance benchmark. This level of performance is rare, and rarer still is the filter that will maintain this over any significant quantity of water passing through.

Making Do with a Lesser Filter

Let’s face it, you might not currently possess a filter capable of true nano-scale filtration. Alternately you might have a high-performance filter that is overdue for a filter change, or has just been through so much you frankly lack confidence in its upper-end capabilities. What then is a concerned and savvy prepper to do?

That part is easy. You can simply filter your water as best you can using what resources you have available before passing it through your dedicated water filter.

If there is then any doubt that the filter has not reliably performed at the level which will assure you that viruses are no longer present, all you will need to do then is boil the water prior to drinking it.

As a rule, viruses cannot survive high temperatures, to say nothing of the raging temperatures of boiling water.

Unlike what is commonly recommended, you don’t need to boil your water for ten minutes, half an hour or anything like that; simply bringing it to a boil and keeping it there for a minute or two is more than enough to ensure all viruses are destroyed, and after it cools your water will be fit for drinking.


The right water filter can remove viruses from your water source. The filter package in your filtration device must simply be capable of nano-level filtration in order to ensure that all viral contaminants are removed.

Lacking this level of capability, a lesser filter can be used prior to boiling the water in order to destroy any viruses present.

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