Last Updated on March 24, 2021
Water, food, fire, and shelter are the cornerstones of any outdoor adventure. One quart of water weighs 2 pounds, which is a lot of extra weight to carry on a hiking trip or a wilderness excursion. It may be more convenient to find a source of potable water in the wild. There’s also the possibility that daytrippers, hikers, campers, and even experienced outdoorsmen can find themselves in an unplanned situation with no safe water. You may locate a source with little effort, but the question remains: how can you tell if water is drinkable?
The Need for Drinkable Water
We can survive for weeks without food, but only for a day or two without a source of water. Not only does a lack of water lead to dehydration, but our water intake regulates body temperature, improves physical and cognitive performance, and prevents hypothermia and hyperthermia. Whether you find yourself unprepared in the wild or bunkering down for a survival trip, one of your very first priorities should be to find a water source.
Unfortunately, most water found in the wilderness is unsafe for drinking. At best, it will leave you with gut ache and diarrhea, but considering diarrhea also depletes the fluid in your body, this can be extremely dangerous as well. Water can contain microscopic pathogens, and just because a stretch of the river appears to be free from contaminants, does not mean that the same is true a few hundred yards upstream.
Many of the dangerous pathogens found in wilderness water are microscopic, which means that you cannot see them with the naked eye. No matter how clear a water source looks, it could be harbouring invisible bacteria.
With that said, while flowing water that looks crystal clear and has no surface scum may not be guaranteed to be safe, it will be safer than standing water that is murky and cloudy. The following visual cues will help you determine if the water is drinkable.
Scan Your Surroundings
Always look for signs of contaminants in the surrounding area. Dead animals rot and they leak bacteria into the water, which then spreads. Look for signs of animal carcasses, and remember that bacteria like cryptosporidium can be spread through animal fecal matter, so look for obvious signs of poop.
Avoid Sources Near Urban Areas
If water passes through built-up areas or even under roads, it is likely to have picked up contaminants and should be avoided. This is also true if the water passes factories or industrial complexes. This water could contain chemicals, and even boiling this water may not prove effective in making it safe.
In a life or death situation, your preference should always be to drink risky water rather than suffer serious dehydration.
Carry a Testing Kit
You can buy water testing kits. Typically, these are small strips of paper. You wet the paper, wait the required time, and compare the color of the paper to a provided chart. These will help identify common bacteria like salmonella, but they won’t necessarily catch every contaminant that you would find in wilderness water supplies.
Good Water Sources
Streams, rivers, and lakes are the most obvious sources of wilderness water. Remember that clear, flowing water is your best option. Movement minimizes the chance of bacteria being able to breed and grow, although it doesn’t completely eliminate this risk. Small streams are your best bet. These are flowing, and do not usually pass through towns and cities, so they should have minimal pollution.
Rivers can suffer from increased pollution because they are more likely to pass through large towns. Lakes and ponds should be your final option. They will provide water, but because they are stagnant, this means that there is a much higher risk of bacteria and other contaminants.
Is Rainwater Safe?
Rainwater is safe, although it may become polluted if you are in a city or busy area. If you have any kind of container, place it in an open area and allow the rainwater to collect.
Alternatively, you can attach a tarp or another waterproof cover to trees, tying the cover in each corner. Allow one end to sag so that it creates a river of rainwater that drips, or runs, down into your water bottle or another container below.
Other Natural Sources
Morning dew is also safe. It can be more challenging to collect, but if you tie absorbent clothes around your ankles and walk through long grass. Wring out the water when the clothes are fully soaked and repeat. You can collect as much as a quart of water every hour with this technique.
Water from Plants
Plants release water through their leaves in a process called transpiration. Tie a bag around the foliage of a large leafy bush or tree. Place a small rock in the bottom of the bag so that the water has somewhere to collect, and then make a small hole in the bottom. Place your container underneath and leave your tree bag to collect water over the course of the day. You may need several of these to get a decent amount of water, but every little bit counts.
Make an Underground Still
You can even make an underground still. Moisture under the ground is warmed by the sun to produce condensation, which is then collected in plastic. The condensation then drips down into your container, producing up to one quart, per still, per day.
Snow and ice can make good water sources. Look for clean-looking snow, and always ensure that you melt it before consuming. Ice can seriously lower your body temperature, and dehydrate you, rather than replenish your water supply. Also, do not use sea ice.
How to Treat Water
Regardless of your collection technique, you should treat any water you gather, before consuming it. If this isn’t possible, and your option is dehydration, then you are better drinking the suspect water rather than doing without.
The simplest and one of the most effective ways of treating water is to boil it. Ideally, you will have something like a metal pan or water container, but this won’t always be the case. Use a metal tin, if you have one. Alternatively, a large shell can be used to boil small amounts of water. A glass jar or other glass container will also work. Even a plastic bottle can be used. Ensure that your plastic bottle is filled with water before replacing the lid and then heating it in coals. The lack of air should prevent the plastic from melting and leave you with potable water.
If you have a chance to prepare, take a fire starter like a ferro rod. These will work in any weather conditions and do not require a fuel source to work. If you don’t have any method of making a fire to boil your water, place it in a clear container and leave it in direct sunlight to at least kill off some bacteria.
It is possible to filter out large debris and contaminants using a sock or other item of clothing, but this will do little to remove bacteria. Fill your sock with sand or grass and then run your water through it, collect it in your water bottle, and drink. It might not taste great, but it could minimize the risk of illness and slightly improve the quality of your water.
Pop some water purification tablets in your backpack. Ideally, you should strain any large pieces of debris out of the water before you purify it using the tablets. It may take more than one tablet, depending on the condition, and purification tablets usually take half an hour to be effective. You should also ensure that the cap and rim of the bottle have been purified.
Whatever method of purification or treatment you opt for, filter the water from one container to another and back again. Keep doing this. It doesn’t improve the purity of the water, but it adds oxygen to the water supply and will improve its taste.
Harness the Power of the Sun
The last and most time-intensive way to treat water in the wild is to use the sun’s ultraviolet radiation. This process, also known as solar water disinfection, will require some kind of clear plastic or glass bottle. The water itself should also be clear and free of debris, so you’ll need to filter it before trying this method.
Collect up to 2 quarts of water in a jar or bottle and leave it in an area with full sun exposure for a minimum of one day. Obviously, if you’re in a survival situation, you may not have the tools or the time for this method, but it has proven effective under the right conditions. Be advised that solar water disinfection only works for quantities up to 2 quarts.
How to Tell If Water Is Drinkable in the Wild
If you have a chance to prepare before being left in the wilderness to fend for yourself, you will have a means of making fire, gathering, and holding water. In this case, finding the cleanest and best possible source of water, and then boiling it and letting it cool, will yield the safest water. If you’re stuck and had no chance to prepare, you should remove large pieces of debris before leaving water in the sun, or gather rainwater and plant water to survive on. You can get away with drinking urine, but this will only help you for a day or two before it makes you sick.
David Slone runs the TapIt Water blog. He first learned about water filtration and the impact it has on the world in college. Ever since that day he has worked towards making the world a better place. He writes to inform you about water filtration, the consequences of plastics, bottled water, and how we can do things better.
He loves to spend time with his beloved wife, 3 kids, and dog when he’s not writing.