Finding Safe Water to Drink Outdoors: A Guide

Young woman drinking water from outdoor stream with her hands

If you’re an avid hiker, camper, rock climber, or backcountry four-wheeler, then you’re probably aware that it is essential to have plenty of safe drinking water with you at all times. So, what do you do if you run out of bottled water?

Finding safe drinking water outdoors is all about preparation. Pack as much bottled water as possible, as well as purification tools for disinfecting natural water. Boil, filter, or chemically treat the water to rid it of dangerous, disease-causing bacteria. Never drink standing water.

Staying hydrated is one of the best ways to ensure that the time you spend enjoying nature is pleasant and safe. Should you run out of the water you packed, here’s a guide on how to find more and how to properly purify it.

Be Self-Sufficient

Being prepared is the best way to stay safe. This is true for all outdoor activities, especially when it comes to having drinking water on hand. According to The National Academies of Science, Engineering, and Medicine, men need to drink about 125 ounces (3.7 liters) of water per day, and women need to drink about 91 ounces (2.7 liters). Young children need a minimum of roughly 8 ounces of water times the number of their age, so a 3-year-old would need at least 24 ounces of water per day, a 5-year-old would need at least 40 ounces, and so on. Knowing this, plan accordingly on the amount of water you will need for all people in your party, no matter the outdoor activity.

Before your outdoor adventure even begins, fill your backpack or cooler with reusable water bottles. As a simpler rule of thumb, bring 1-2 water bottles per person for every hour you plan to spend outside, especially if the weather is hot and/or dry. It’s also a good idea to pack extra water bottles in case you encounter anyone in danger of heat stroke or dehydration.

If you’re a hard-core adventurer and you need your hands free for the activity (i.e. bicycling) a CamelBak might be well worth the investment. These backpacks are specifically designed to carry 50-85 oz of water and have an over-the-shoulder tube that allows you to take regular drinks without having to stop.

If you’re planning on going camping, fill at least one cooler completely with fresh water. Use a cooler that has a nozzle for drink dispensing so that you can refill water bottles. This will save you space since an extended stay outdoors would require a lot of water bottles, and it will also reduce plastic waste.

If you’re already outdoors and you’ve run out of water, retroactive preparation really isn’t an option. So let’s talk about what else you need to know, and what options are available to you.

Avoid the Danger Zones

Boy scooping water from the lake ,drought and global warming.

When searching for safe water to drink outdoors, avoid areas where the water will be dangerous to drink. Certain bodies of water cultivate dangerous bacteria that can cause severe illness. Always avoid drinking water from the following areas:

  • Stagnant ponds – Even if the surface is clear, stagnant ponds are home to all kinds of contaminants that will make you sick.
  • Camping areas – Never drink water that is downstream from a public camping area. Even if there are bathrooms and rules for waste disposal, that does not mean that everyone acts responsibly. The water could very likely be contaminated with urine or feces.
  • Mining areas – The water supply around mining areas, or even areas where mining once occurred, will likely be full of loose sediment and dangerous chemicals. These kinds of minerals are not healthy for you to ingest.
  • Unsewered towns – Some small towns near camping sites or in rural areas do not have sewage systems, which means natural bodies of water nearby could very likely be contaminated.
  • Odorous water – Even if the water is free-flowing and clear, never drink it if it has an unusual odor. This could indicate that an animal has died upstream and the river is carrying bacteria from the carcass, or that the pH level is not human-friendly.

Always check the appearance and location of a water source, using your common sense to assess factors that may affect the water quality. Think before you drink. Even river water, bore water, or spring water can cause illness if it is untreated; this is not worth the risk, no matter how thirsty you are.

Know the Risks

All of these warnings might sound like paranoia, but once you know the risks associated with unclean water, you’ll understand why purification is so vital. Waterborne organisms like Cryptosporidium, Giardia, and E. coli can cause a range of miserable symptoms such as nausea, vomiting, trembling, stomach pain, and diarrhea. Other waterborne chemicals could cause long-term illnesses that are more severe, like kidney damage, liver failure, nervous system damage, and birth defects. Pregnant women, elderly people, and young children are particularly at risk for incurring these symptoms from untreated water.

The most common sources of dangerous protozoa are human and animal fecal waste. To eliminate the risk of exposure, always bury human waste in the ground at least 8 inches deep and at least 200 feet away from lakes, rivers, and other natural bodies of water. This will help prevent dangerous chemicals from seeping through the soil and into the water supply. Always wash or sanitize your hands before handling food or eating, and especially after using the toilet. Keeping germs off of your hands is a proactive way to help keep germs out of your water.

Whenever possible, drink water from a regulated system that is monitored by public health regulations. Even if local residents are accustomed to drinking from a natural water supply, that does not mean that you will be safe drinking from it as well. As an outside visitor, your body is not accustomed to the water local residents may be drinking, and your immune system will not be able to process it without having some kind of reaction. To be smart and safe, locate a body of moving water, and proceed to complete any of the following water disinfection/purification methods.

Use a Disinfection Method

boiling water in a pot on the fire

The four primary methods for disinfecting and purifying water are boiling, chemical treatment, ultraviolet light, and filtration. Each of these methods is designed to kill dangerous bacteria and remove harmful minerals from the water, and each method is verified by the CDC as a tried-and-true approach to safe water treatment.


Boiling water is perhaps the oldest, most well-known way to make it safe to drink. It is an effective way to eliminate most microbial contaminants such as bacteria, viruses, and protozoa. This water disinfection method is also popular because it is the easiest; all you need is a simple campfire and some clean containers.

If you are camping or backpacking, bring a pan that you can use over the fire to boil water. Bring the water to a rolling boil and let it boil for at least one minute, or three minutes if you are at an altitude above 5,000 feet. Remove the water from the heat and let it cool naturally. Once the water is completely cool, pour it into clean containers and secure them tightly with lids or coverings. The water is not completely free of bacteria, but the bacteria are dead.

With the bacteria killed, the water is most likely safe to drink. If the water source was contaminated with poisonous substances like arsenic or lead, boiling it will not make it safe to drink. This is why it is important, as mentioned previously, to collect your water from a safe source.

Some people have observed that, when purified through boiling, water can taste particularly flat. To improve the taste, add one pinch of salt per liter of water. Pour the water back and forth between containers to mix it until the salt dissolves.

Chemical Treatment

Most major outdoor retailers and suppliers will carry tablets that can be used for chemical water treatment. These tablets consist primarily of chlorine and iodine. These tablets come in bottles and have expiration dates, so make sure that you are using the verified products within the timeframe that they will remain effective.

Treating water with chemical tablets is all about how clear the water is, the temperature of the water, and the pH level of the water. If the water you have collected is particularly cloudy, strain it through a cloth prior to treating it. This will help separate some of the particles that will be harmful to ingest.

Following the directions on the label of the bottle of tablets, add the chemical to the water in the correct proportions. (This is where it would be handy to have a measuring cup or some other container with a clear measurement for liquid.) Swish the chemical around in the water to help it dissolve and to help it treat the inner side of the lid as well. Let the water sit for at least 30 minutes after the chemical has dissolved.

If the water is cold, chemical treatment will not be nearly as effective. Studies have shown that in water that is 50°F or colder, less than 90% of bacteria were eliminated. Warm your water in the sun or over a fire prior to chemical treatment to make sure that it is as least warm enough to react with the tablets. It works best when the water is 68°F or warmer.

If you’re using iodine, be aware that some people are allergic to iodine. It is also not safe for women who are pregnant to ingest iodine-treated water, so if a member of your party is pregnant, prepare an alternative means for water purification.

You can also purify water with a few drops of bleach, in an emergency. In this case, it is critical that the ratio of bleach to water is absolutely correct. Use a dropper tool and bleach that has been stored at room temperature for less than one year. Bleach can contain either 6% or 8.25% sodium hypochlorite. Refer to the details on the bottle and this table for the amount recommended by the EPA, based on the percentage contained in the bleach:

Volume of WaterAmount of 6% BleachAmount of 8.25% Bleach
1 quart/liter2 drops2 drops
1 gallon8 drops6 drops
2 gallons16 drops (1/4 tsp)12 drops (1/8 tsp)
4 gallons1/3 tsp1/4 tsp
8 gallons2/3 tsp1/2 tsp

Ultraviolet Light

Ultraviolet light is used in sterilization methods for hospital equipment and other professional materials. Radiation from UV light kills microorganisms, which is why some water filtration products have been designed to use it. A Hydro-Photon Steri-pen is a battery-operated UV water purifier that kills protozoa, bacteria, and viruses. It should also be noted that, while the UV light is safe to use underwater, it can be dangerous to your eyes and skin if turned on outside of the water. By using a small amount of UV light, you can use this tool to disinfect water in as little as one minute. However, since UV light cannot kill bigger particles, this method is not effective on cloudy or discolored water. That’s where filtration comes in.


Water filters have been invented to pump water through a microscopic series of filters and strain out organisms of a certain size. Some filters are designed to remove silt and small minerals from water, while others are advertised as purifiers and can safely strain out microscopic organisms. It’s important to know the difference in what the product is capable of and what kind of water you intend to use it for. And while filtration devices and straws can be exciting, be sure to still locate the cleanest water you can find. Dirty water will clog your filter and render it useless in a much shorter amount of time than regular, conscientious use.

Where to Get Help

If all else fails, or you still have questions and want to be absolutely sure of your options before making a fatal mistake, contact the Department of Health and Human Services and ask for the Water Unit. You can also ask any professional at a local camping or outdoor gear supplier, as well as any member on your local Environmental Health council.

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