How to Purify Water – Making Water Safe to Drink

Categories: Outdoor Survival


In this post you’ll learn how to purify water using proven methods.

When disaster strikes, unless you have stored water for emergencies, safe drinking water isn’t always going to be available, however, water that is dirty and/or contaminated could be; and it might be the only water you have!

Drinking contaminated water is just as dangerous as not drinking any at all; but if it’s a tossup between living and dying you really won’t have a choice, you simply have to drink water in order to survive.

Water purification saves lives and should you ever find yourself in a survival situation where you have no choice but to drink whatever water you can find, knowing how to purify water could very well save your life too!

Let’s dive right in!

Why is knowing how to purify water so important?

Surviving for a few weeks without food may well be uncomfortable but it is certainly possible if absolutely necessary. Surviving without water for any longer than 3 or 4 days however, is extremely difficult, and beyond 8 days is virtually impossible.

Needless to say, it is imperative that you find water as quickly as possible in order to ensure your survival.

Unfortunately, in many survival situations, particularly those in urban locations, it is highly likely that a lot of the water you will find is not going to be 100% safe to drink, not even close to it!

You may start to think yourself lucky because you have what seems like a nice clear stream, river, or a lake nearby, but nowadays, as clean as they may seem, without proper filtration and purification none of those sources could be deemed ideal for drinking water.

If you know how to purify water, then even the dirtiest of ponds can provide you with a lifeline of potable (drinking) water, ensuring your survival and those you are responsible for.

Understanding the difference between purification and filtration

Before covering the different ways to purify water it is very important to note the difference between purifying water and filtering water.

Filtration will remove debris from water and, depending upon the level of filtration, can also remove waterborne parasites and bacteria, but not viruses; as such, filters will make water much safer to drink; but not 100% safe.

Only purification will be able to eliminate viruses as well, doing so will make water completely safe to drink.

However, it is very often the case that any water you’re intending to purify will contain a lot of debris, in which case it is always advisable to filter your water in order to remove as much as possible before any purification treatment.

Water purification methods

Water purification is the process whereby all dangerous pathogens and viruses are destroyed, making water safe to drink.

There are basically three ways to purify water: boiling it, treating it with chemicals, or exposing it to sustained ultraviolet light.

Boiling water

water purification - rolling boil

Boiling water is the most basic of purification methods but also one of the most effective. One minute of a rolling boil (three if at high altitude) is all that is needed to purify water according to EPA guidelines.

As simple as this sounds, there are downsides. You will require heat of some kind in order to boil your water. If you don’t have the equipment to boil your water or you are unable to have or start a fire for whatever reason, then you will have to look at alternatives.

However, if you are able to boil water then you should also make allowances for water loss. Boiling will lose a percentage of your water through evaporation. This may not be a problem if water is plentiful, but if it is in short supply, an alternative method of purification may again be needed.

Water purification tablets

Chlorine# Dioxide Water Purification Tablets

One of the easiest ways to purify water is to use water purification tablets. Water purification tablets are most commonly made from chlorine dioxide, although iodine tablets are also available.

They are extremely simple to use, in most cases just drop a tablet into a quart of water, wait for the recommended time, which will generally be around the 4 hour mark, and your water will be completely safe to drink, having had any harmful pathogens and parasites completely eliminated.

The obvious downside to using chlorine water purification tablets is the time that it takes to make the water safe before you are able to drink it. They are also generally more expensive than other purification options if your budget is an issue.

However, there are benefits to using chlorine purification tablets; they have a long shelf life, and they don’t leave a nasty taste in the water once the purification process has completed unlike iodine.

They are also perfect for storing in your emergency gear or your bug out bag.

Iodine drops

Iodine is more effective than chlorine at purifying water but that doesn’t necessarily mean it’s the best choice!

Iodine is readily available in small bottles which are perfect for storing in your emergency gear. Not only can iodine be used to purify water but it is also a great anti-sceptic solution useful for cleaning and sterilizing cuts and grazes.

Iodine drops water purification

When used for water purification you simply need to add around 5 drops for each quart of water, 10 drops if the water is extremely cloudy. Thirty minutes is generally enough time for the iodine to kill off anything harmful lurking in the water!

Unfortunately, iodine does leave a bad taste in the water and will take some getting used to which is fine for adults but isn’t ideal when you are trying to keep young children hydrated.

As well as leaving a bad taste, iodine is not safe for pregnant women and people with an allergy to shellfish.

When you consider the bad taste and the limitations as to who can safely use it, iodine may not sound like the most suitable purification method; but if you have nothing else and there is a bottle of iodine tincture in your first aid kit you do at least have a back up option.

As mentioned, you can buy iodine tablets rather than tincture. These tablets have been produced specifically for the hiking and backpacking crowd. They work in basically the same way as the chlorine tablets, only much quicker and much more effectively, although you will still have to stomach the bad taste. They are also less expensive than their chlorine counterparts!

Chlorine bleach

Chlorine in any form will kill all harmful pathogens found in water and common household chlorine bleach will certainly fit the bill which is ideal as most households will have some in their cleaning cupboards.

Household bleach is available in different strengths so the number of drops per quart will vary depending upon the strength. If your bleach has a strength of 1% or less, then 10 drops will be needed per quart of water, 2-3% 4-5 drops, 4-6% 2 drops.

It is best to use unscented bleach if you can but whatever you have at hand will be good in an emergency.

Solar water disinfection

If you want to know how to purify water using the simplest and most affordable method out there, then the SODIS method is what you’re looking for. The SODIS (solar water disinfection) method is considered extremely effective in eliminating most pathogens using nothing but a plastic water bottle and direct sunlight it’s also one of the simplest ways to do so too.

Solar Water Disinfection

This approach works because of the ability of plastic to contain heat and UV radiation from the sun and use it to kill off bacteria and other unwanted pathogens. Clear PET bottles (polyethylene terephthalate) are your best choice. They will trap the heat and allow the UV radiation to pasteurize your drinking water.

To make the method work, simply fill up a few water bottles and expose them to direct sunlight for about 6 hours. Maximize exposure time by laying the bottles on their side. Once the process is completed, most common viruses, bacteria and pathogens should be eliminated.

The SODIS method has been proven scientifically to work. It’s currently supported by WHO (World Health Organization), and recommended by UNICEF and the Red Cross as the simplest method for achieving clean drinkable water in developing countries.

Water filtration

Survival Water Filter

Water filters, as mentioned at the start of this post, will remove protozoa and bacteria, but viruses are way too small for the filtration process to catch, no matter how good the filter.

However, this level of filtration may be enough but it will depend on where you intend to use your filter.

Generally, water in North America is classed as filtration safe, meaning it does not carry any of the life threatening viruses that can be found in water in other, undeveloped parts of the world. This is why survival water straws such as the Lifestraw and the Sawyer Mini are so popular in the US, they are extremely effective at what they do.

Filtration does have its benefits. It is much quicker than purification, equipment such as personal survival straws enable you to drink immediately rather than having to wait for added chemical treatments to do their work or for water to boil and then cool. Also, filtration has no effect upon the flavor of the water unlike some chemical purification methods, namely iodine.

At the end of the day water filters work; they’re not guaranteed to be 100% effective in making water safe to drink but if there is no other way to purify your water and you’re in the US or Canada you’ll likely be fine with a survival filter.

However, if you have the means to purify your water also, then do so, it is always better to err on the side of caution.

How to Purify Water

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