How to Purify Your Water Supply

The Good, the Bad, the Stagnant and the Salty: How to Purify nearly any Water Supply

Eventually, when your clean water supply runs dry you’re going to need to seek out and procure a new source. No matter what your circumstance, it is best to always purify your water before consuming it.

Water comes from two sources: ground or surface. Whether it comes from a river, a well, mountain stream, rain run-off, or from a stagnant source such as a radiator, backyard pool or floodwater, you’re going to want to make sure it does not contain contaminants or bacteria.

Devices that can turn any source of water into a potable beverage quickly and safely vary in price and can be simple to complex, depending on the source water. If you’re not savvy enough or do not have the mindset to build a water purification/recovery system for your domicile—or if you are constantly on the move and a large system is impractical to transport—there are plenty of options to make sure the water you are drinking won’t do you physical harm or cause death. Below are some of your options.

Good Water Source
Your best water choice is always from a clean source, such as springs, reservoirs, and wells. Purification of a natural untreated water sources is much simpler, the most convenient and the least expensive. You can add a few drops of bleach* or calcium hypochlorite (aka pool shock) to the source and boil it.

There is also chlorine dioxide water purifying tablets, and if you want even further protection you could also use an inline water filter that uses antimicrobial technology that removes 99.9% of harmful giardia, cryptosporidium, and other contaminants down to 0.3 micron—added protection for your hydration pack or non-filter carry bottle.

* A little known problem with storing bleach long term is that it degrades over time. Many survivalists choose to use calcium hypochlorite because not only destroys a variety of disease causing organisms including bacteria, yeast, fungus, spores, and viruses, it is also cheaper with a little going a long way.

Bad Water Source
If you have a dirty water condition or a questionable source—such as a cistern—you will need a more robust approach to purifying your water. A ceramic water filtration system, whether a water filter bottle or hand pump apparatus, with the filtration efficiency of 0.2 micron and silver impregnated—which does not permit bacteria growth-through mitosis for all microbiological organisms—is most desirable. Most ceramic elements may be cleaned 100 or more times with a soft brush or damp clothe.

Stagnant Water Source
For the worst water conditions, you will need a water filter system specifically designed to make safe drinking water from almost any water source.

The filtration system you purchase will need to eliminate bacteria, protozoa, cysts, algae, spores, sediments, parasites, fungi, viruses, microbiological waterborne pathogens, and also reduce chemicals and radioactive particles. There are two major players on the market; one that uses a silver impregnated ceramic depth filter element (with optional carbon filter) and the other uses a proprietary system of ultra filtration membranes with a replaceable activated carbon filter.

katadyn How to Purify Your Water Supply zombie education alliance

Katadyn North America is the name brand in this field; they have been making ceramic filters since the 1930s. Name recognition and history, not necessary innovation, has made them the industry front-runner. Their products are time tested and field reliable. However, there has arisen a new kid on the block. In 2007, Lifesaver Systems UK came out with an ultra filtration bottle, followed by a jerry can, both of which are in service with British Forces.

Comparing the Katadyn Pocket Water Microfilter to the Lifesaver bottle there is not much difference. Bacteria and virus retention are nearly identical. The Katadyn Pocket filters parasites, algae, pollen, fungi, asbestos fibers, nuclear explosion debris, invisible dust particles as well as larger suspended particles and sediment, whereas, the Lifesaver filters bacteria, viruses, cysts, parasites, fungi, and all other microbiological water-borne pathogens. The Lifesaver also reduces a broad spectrum of chemical residues including pesticides, endocrine disrupting compounds, medical residues and heavy metals—but so will the Pocket if you purchase the optional carbon filter.

lifesaver How to Purify Your Water Supply zombie education alliance

You will find the Lifesaver is significantly cheaper, has a flow rate is 1.5 times that of what the Pocket does, and operates on a small amount of pumps vs. non-stop pumping on the Pocket. But the most significant feature is the Lifesaver filters particles much smaller in size (0.15 micron vs. 0.2 micron for the Pocket).

Both filtration products have their pros and cons. Many swear by their Katadyn system, while other think the Lifesaver is the better product. But remember, whatever you may choose, think smart, shop wisely, stay vigilant, and be safe.

Salty Water Source
Sometimes in a survival situation the only water source you can find is seawater. While humans can safely ingest small amounts of salt, the sodium chloride content in seawater is much higher than what can be processed by the human body. Seawater also contains potassium salts, epsom salts, iodine and magnesium salts. A kidney cannot make urine from a concentration of salts of more than 2%. Seawater is made up of approximately 3% salt. Therefore, to get rid of all the excess salt taken in by drinking seawater, you have to urinate more water than you drank. Eventually, you die of dehydration even as you become thirstier.

This would mean that you can never drink saltwater would be true. Well, in part. In order to drink seawater you would have to dilute it to a 10:1 ratio. This may sound pointless and somewhat ridiculous, but think about it. If your water supply is running low and you have no apparatus to desalinate what is around you, then extending your water supply even by the smallest portion could save your life.

However, you don’t need complicated equipment to desalinate seawater. There are two easy solutions for extracting fresh water from salty. The simplest method is utilizing a few household items to make a condensation bucket/bowl, also known as a solar condensation still.

There are six simple steps to the build:
1) Find a bucket or bowl (plastic, metal, ceramic).
2) Place a cup in the center of bowl (plastic, metal, glass).
3) Fill the bowl with salty water, but do not go over the height of the cup. Less water will distill faster.
4) Cover the bowl with heavy plastic or tin foil, but do not wrap it too taut (inverting a raised lid will also work).
5) Place the still out in an area that receives a lot of sun.
6) Place a small weight (rock, metal washer, etc.) on the center of your plastic wrap or foil cover. This will funnel the condensation into your collection cup.

solar still How to Purify Your Water Supply zombie education alliance

Through the process of condensation the pure water will collect on the plastic wrap and drip into the cup, giving you desalinated, drinkable water. The process is slow and the yield is not great, but every ounce it produces can help you survive.

A more productive method, which can give you a greater yield of desalinated water is through a distillation boiler/still. A distillation still is not unlike a solar still, saltwater is heated, it vaporizes and then is collected. However, building one requires a heat source other than solar energy along with a pot and lid, vent tubing and a catch basin.

Sourcing these materials may require some work if you are in a survival situation. If you are on a boat lost at sea your galley may have what is needed. If you are stranded on a coastline, it may be to your advantage or disadvantage, depending how much debris has washed up on shore.

A capped, large plastic soda bottle can substitute for a boiling pot and lid. Just remember the height of the flame cannot exceed the water within the bottle or you’ll have a meltdown. For venting the shaft of a pen or rubber tubing can substitute of a copper coil, and a coffee can, 12 oz soda can or even a Styrofoam cup can act as a collection basin.

Here are steps to build an improvised still:
1) Fill a 2 liter plastic bottle with saltwater to mid-point and cap it.
2) Puncture a hole into the bottle several inches above the water line the size of your venting tube.
3) Insert your venting tube or pen shaft.
4) Place the bottle on a low open fire (gas burner or coals).
5) Position your vent shaft/tubing above or into your catch cup.

The steam will rise from the boiling water, be forced out through the venting shaft where it will reconstitute as a liquid and be caught in your collection vessel. Ideally a condensation unit/cooling container could be used to cool the steam as it travels through the vent, but that is not always possible under certain extreme survival conditions.

Survival Still How to Purify Your Water Supply zombie education alliance

There are several companies that make survival stills for purification and desalination purposes. One in particular is the Survival Still by SurvivalStills (drawing above). Or you could DIY one for home use like inventor Deris Jeannette did with his ClearDome Solar Pure Water Still/Pasteurizer.

stove top still How to Purify Your Water Supply zombie education alliance

About TS Alan

TS was the former managing editor of Zombie Training before co-founding ZEA with former associate editor Mike Garman. TS was born outside Buffalo, NY. After attending high school he entered into a two-year community college to study Communications and Media Arts. There he became involved in the college’s radio station as a radio personality, under the pseudonym of J.D. Hollywood. After a year with WNCB radio he also became the station’s Promotions Director. J.D. Hollywood was also one of two names he used as a music reporter and Associate Editor for Buffalo Backstage, a local music magazine. After moving to Manhattan and experiencing the Northeast blackout of 2003, he became interested in prepping and urban survival, learning much of his experience through self education and observation of tragic events like 9/11 and Hurricane Sandy. TS Alan currently resides in the East Village of New York City and is a published author of the zombie novel The Romero Strain.


  1. Not being a native English speaker / reader, your article is definitely simple for me to understand and that is its greatest strength. Thank you.

  2. This is really an interesting post. Thanks for giving me some info on how to make water drinkable, when it is contaminated.

    Dwayne P.