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Water For Survival

(Last Updated On: December 17, 2019)


Having stored water and knowing how to purify water during a time of disaster is an extremely important skill to have for survival.

Here’s Why:

The human body loses water through breathing, sweating, and waste elimination, so it’s important to replace that water through food and other fluids containing water.

Your body uses water in its cells, organs and tissues to help regulate temperature and maintain other bodily functions. The average human body needs approximately 1.5 liters (about 6.3 cups) each day to replace that water lost.  Hot, dry weather, or heavy work loads (like in a survival situation) can cause heavy sweating, requiring more water. Sickness (diarrhea), or vomiting (Situations we often run into because of unsanitary conditions during disasters) will also require more water needed.


How do you know if you have been drinking enough water?

Your urine should be clear to slightly yellow. Darker urine means your kidneys are making concentrated urine to save water, it other words, you are starting to get dehydrated. Other signs that you may be getting mild to moderately dehydrated are:

  • Increased thirst
  • Dry mouth
  • Decreased urine output
  • Headache
  • Dry skin (loss of elasticity)
  • Muscle cramps
  • Tired or sleepiness
  • Dizziness
  • Rapid heart rate of heart palpitations

Severe dehydration will lead to the body’s organs to begin to shut down. Lack of body fluid can lead to the volume of blood becoming so low that the brain and other organs are not able to recieve the oxygen they need causing the body to go into shock. This can cause complications like loss of consciousness, brain damage, kidney failure, and heart attack.

So How Much Water Do We Need?

We use a lot more water each day than you may think.

The average American family uses more than 300 gallons of water per day!

About 70% of that occurs indoors.

We get up in the morning, use the toilet, take a shower, brush our teeth, grab a cup of coffee, cook, wash our dishes and clothes, and a variety of other uses.

Outdoors we are watering our lawns and gardens, washing our cars, filling our kiddie pools, and other uses. That uses approximately the other 30% of our total personal water use.

Obviously, in a disaster or survival situation, we can drastically reduce that amount.

But even so, we are still going to need a minimum of 1 gallon of water per person per day.

That’s only 1/2 gallon (8 cups) for drinking and cooking, and 1/2 gallon for hygiene (brushing teeth, washing, etc). That’s not much water when you consider just flushing the toilet uses 1.6 (new efficient toilets) up to 7 (older toilets) gallons of water.

So if we want enough water on hand for the 72 hours minimum recommended during a disaster, each person will need 3 gallons. For a family of 4, that’s 12 gallons of water! During a disaster, we can’t plan on just getting that water out of the faucet. It may be contaminated (floods, etc.)(and remember Flint, Michigan’s water problems), or not flow at all (broken pipes, no electricity to pump the water, etc.).


We need to do 2 things to have the water we need for survival.

  1. Store water. Store enough water to provide for our needs.
  2. Purify water. Collect and purify water to replace our needs when our stored water runs low.

How To Store Water

Bottled water. Pre-packaged bottled water is one simple way to buy and store water. You can easily stack a few cases on the floor of your pantry or closet, under the bed, etc. Check expiration dates and rotate and replace as needed. Keep bottled water out of the heat and sunlight to prevent deterioration of the bottles. (Water bottles stores in vehicles need to be used and /or rotated out very often because of the heat buildup in the vehicles.) Water itself doesn’t have an expiration date, it wiil store indefinitely, but the plastic it is stored in may eventually leach chemicals into the water. If you stock your water this way, you should make sure that you rotate it by using the oldest first and replacing it with new.

Fill Your Own Containers. You can purchase the 5 gallon or 6 gallon containers  often used for camping to store water. You can also use 2-liter plastic soda bottles. Always completely clean your containers before storing any water in them. Wash with soap and water and then sanitize them with a solution of 1 teaspoon of non-scented liquid chlorine bleach added to a quart of water. Rinse with clean water.  It’s best to replace the water in these containers every 6 months. Again, store in a cool, dark place.

Don’t use milk jugs or containers that have had other foods stored in them. They are difficult to clean and can easily harbor bacteria that can contaminate your water. Also don’t use any non food-grade plastic containers or containers that have ever contained anything poisonous in them.

See Best Water Storage Containers article

 20 to 55 Gallon Barrels are available as a great way to store water in your home or if you have a permanent bug-out location. With their large size and weight (water weighs about 8.3 lbs per gallon), they are difficult to move or take with you should you have to evacuate you location.

Bath tubs are another place to store water if you have some advance notice of an emergency or disaster situation. For example, if you were in the path of a hurricane and knew there was the potential of your regular water source being cut off due to flooding, you could fill you bath tub with water and often have up to 100 gallons of water. There are even commercial storage kits like the waterBob that are made to fit inside your tub to keep the water stored in them free from contamination.

Larger storage containers are available to store up to 525 gallons of water for the serious preppers. For a family of 4, that would be over 130 days of water available! (At the recommended minimum of 1 gallon per person, per day.)


Water Purification

Unless you have been able to store up very large amounts of water, during a prolonged disaster situation you will need to get more water and will  probably need to purify it to make it safe to drink. If you’ve had to evacuate you home (bug-out), being able to purify your water will be even more critical to your survival.


Why Are We Purifying  Water?

Water may look clean and safe to drink, but it can contain a number of microscopic pathogens. Ingesting just a small amount of disease causing microorganisms can cause sickness and diarrhea and other symptoms causing dehydration. These pathogens or microorganisms fall into three basic categories.

  1. Protozoa: Cryptosporidium parvum and Giardia lamblia are two common types often found. Because they are a bit larger, they can easily be filtered out of contaminated water.

    Giardia lamblia

  2. Bacteria: Escherichia coli (E. coli), Salmonella, Campylobacter, and Shigella are some more common types of bacteria. These are a more midsized microorganism, but can also be filtered out of water.
  3. Viruses: Hepatitis A, Rotavirus, and Norovirus are some types of viruses found in contaminated water. These are very small microorganisms and are very difficult to filter out of water. For these we will usually need some other methods other than just filtering the water to purify it.



Where To Find More Water

First, you will need to find more water. Here are a few sources to consider finding more water. Have a plan in place and know where you can find water in your local area. Remember, everyone else will be in the same situation of needing water, so have several back-up sources.

Water heaters. You can drain the water out of the bottom of your water heater and usually have 30-40 gallons of water available.

Wells. Remember that you will need to pump water up from your well. If the electricity goes out, you will need an alternate source of electricity to run you pump or will need some sort of hand pump to get your water. Also, beware that well can often become contaminated during a disaster (ie. flood).

Rainwater. Some people have barrels set up to catch rainwater to use. You can also use plastic sheets,  large plastic bags, tarps, etc. to catch rainwater to use. Rainwater can be contaminated as it was falling, (through trees, off roofs, even picking up contamination in the air, etc.), so it should be  purified to be safe enough to drink.

Snow, sleet, hail and ice can all be good sources of water. Fresh snow can be melted for drinking , but may still carry a risk of  harboring bacteria it has picked up while falling or sitting on the ground..

Transpiration. Transpiration is where water evaporates from the leaves and stems of plants into the atmosphere. This water can be captured by tying a clear plastic bag around the leaves and branch of a plant and allowing the water vapor released through transpiration to collect on the inside of the bag and collect on the bottom.

Solar still. Solar stills work in a similar way to collecting water through transpiration. With a solar still, you will dig a hole or pit in the ground. In the center, you will put a container to collect the condensed water from the still. Cove  the hole or pit with a plastic sheet and anchor down the edges with dirt, rocks, stakes, etc. In the center of the plastic sheet, place a weight, like a stone, so that the lowest point of the plastic sheet is directly above your water catching container. This will work like a greenhouse, where water from the soil, or plants placed under the sheet, will condense on the bottom of the plastic, run down to the center of the plastic sheet to where the weight holds it down. From there it drips into the container you have placed underneath, giving you safe water.

Swimming pools. Pools can be a great source of water, but you must be aware of chemicals that may have been added that can make you sick.

Springs. Water coming from underground springs are often safe in most areas.

Rivers, lakes, streams, etc. These can be good sources of water, but again be aware of chemical contamination that is often hard or impossible to filter out.

Fire hydrant. If there is still water pressure and you have the tools to open a hydrant, that is another potential source of more water.

Tapping trees and plants for water: Some types of trees and other plants can contain some water.

Dew Collecting the dew off of the grass and other vegetation in the early morning is another way to collect smaller amounts of water to supplement your need.



Purifying Water To Make It Safe

Once we have found more water, we need to purify it to make is safe to use.

There are 3 basic ways to purify water:

  1. Heat
  2. Mechanical Filtration
  3. Chemical Purification


Boiling water is probably one of the most reliable methods to make your water safe to drink. Most health organizations, including the Center for Disease Control, (CDC) recommend you boil water vigorously for  at least 1 minute for elevations up to 2,000 meters (6,562 feet), and for 3 minutes at elevations higher than that. You’re guaranteed to be safe from giardia and crypto if you follow those guidelines. To improve the flat taste of boiled water, pour the water back and forth in two clean containers several times.

Distilling. Distillation is one of the best methods to purify water. You are boiling the water, which kills most biological contaminants like bacteria, viruses, and parasites, and catching the steam as it condense into your purified water container. This will leave behind, in the original water container, about 99% of pollutants, including many chemicals and minerals. It should be noted that some chemical pollutants, such as benzene, toluene, and some pesticides that have a boiling point near or below water, and will turn to steam and also be condensed into your “purified” water container.

Solar Still. A solar still can be used to collect water from the ground, leaves and other organic matter, and it can also be used to purify contaminated water you may have. You could also make a solar still by placing a small clean dish or cup inside a larger pot or bowl.  Place the contaminated water inside the larger vessel being careful not to get any inside your clean cup. Cover the larger pot/bowl with plastic and place a stone or other small object  to form the plastic into a cone shape over the smaller bowl/cup. Let this sit in the sun and the contaminated water will evaporate and form small droplets on the plastic. These will run down the plastic “cone” and drip into the small bowl/cup. Keep in mind that this is a slow process and won’t collect much water very quickly.

In a Disaster situation, it is often necessary to have a backup source of heat. Many times power and gas lines will be out of service and we need to find an alternate source of energy for heat if we plan on using that method to treat our water. See the Power & Energy section on this site for more information on this area.

Mechanical Filtration:

Mechanical filtration is using some type of filter or ultraviolet light to remove contaminants from the water. Many of these filters have pores small enough that they will filter out harmful protozoa and most bacteria. Some of them will even remove some heavy metals and chemicals.  Viruses are too small for the filtration for them to be removed, so many filters will use ultraviolet light or a chemical treatment to kill these viruses.

Pump Filters. Pump filters have an intake hose placed into the contaminated water, and a pump mechanism to pump the filtered water into a water bottle or other reservoir. They use filters with microscopic pores of .2 microns or less that are able to remove protozoa and most bacteria. The filter cartridges are replaceable. (Popular  models include Katadyn Hiker Microfilter, Katadyn Hiker PRO Water Filter, MSR EX Water Filter, MSR SweetWater Water Filter, etc.)

Pump Purifiers. There are some pump filters that will filter out viruses (such as the MSR Guardian Purifier) and some which include a chlorine-based disinfectant solution to destroy the viruses (MSR SweetWater Purifier System)

Gravity Filters. Gravity filters work similar to the pump filters but their advantage is they can handle a larger volume of water. They are good for a larger group. Several companies make these, such as Platypus, Sawyer, MSR, and Katadyn.

Bottle Filters and Bottle Purifiers have built-in filtration or purification elements. Katadyn, LifeStraw, and Platypus make several models of bottle filters. The Grayl Ultralight Purifier Bottle will remove  protozoa, bacteria, viruses, and many heavy metals (lead, arsenic, chromium) and many chemicals (chlorine, chloroform).

Squeeze-Style Filters are similar to bottle filters except you fill a small reservoir and then squeeze the water through a filtration element. Sawyer, Katadyn, and MSR have several models available.

Straw Style Filters (like LifeStraw or Sawyer Mini Water Filters are a fairly inexpensive filter where you can drink the water similar to drinking out of a straw. They are quick and easy, but with some, you are unable to treat water though these for storage or other uses.

Ultraviolet Light Purifier will bombard the water with UV rays to neutralize protozoa, bacteria, and viruses. It works quickly (in about  a minute) and does not leave an aftertaste. It must be used in clear water, so prefiltering is recommended. It does use batteries, so be sure to pack extra spares. SteriPEN makes a number of models to choose from.

Home Water Filter Systems

Many home water filtration systems are available on the market which are great for everyday use. Most of those on the market are designed for removing certain chemicals for taste and odor reduction. Very few are actually designed to be able to remove  microorganisms like protozoa, bacteria, and viruses. Also, in the event of a disaster, there may no longer be running water available to your home, and most of these systems depend on that water pressure to operate.

Berkey Water Filter Systems are designed as a home water filter/purifier that will treat water from such sources as lakes, streams, stagnant ponds and water supplies in foreign countries, where water regulations may be substandard at best. They will work in environments where electricity, water pressure or treated water may not be available. (Like in a disaster situation). The Big Berkey system removes pathogenic bacteria, cysts and parasites and reduces harmful chemicals such as herbicides, pesticides, and VOCs. (VOC’s are Volatile Organic Chemicals (VOCs) are carbon-containing compounds like commercial, industrial and residential products including fuel oils, gasoline, solvents, cleaners and degreasers, paints, inks, dyes, refrigerants and pesticides.)

Chemical Water Treatment

Chlorine dioxide tablets (like AquMira or Potable Aqua Chlorine Dioxide Tablets) are easy to use. Place a tablet into your water bottle. It will take about 30 minutes to kill Giardia, but can take up to about 4 hours to kill Cryptosporidium. 

Iodine tablets (like Potable Aqua Iodine and Taste-Neutralizer Tablets) use iodine to remove or destroy protozoa, bacteria, and viruses. They are NOT effective against Cryptosporidium. Iodine should not be use by pregnant women or people with iodine allergies. Iodine from your medicine cabinet can also be used. Use 5 drops of 2% iodine for each quart of water. (Double it to 10 drops if the water is cloudy)

Chlorine bleach. Treating water with regular, unscented bleach that has not had any added cleaners, soaps, or fragrances (do not use “color safe” bleach) is a good way to disinfect water.

Calcium Hypochlorite (Pool Shock:) This works similar to bleach but has the benefit of the dry granules not degrading and becoming ineffective like bleach does.

Silver Ion Tablets and Colloidal Silver have been touted as ways to purify water. Silver can control bacterial growth and is often used to impregnate the filter cartridges in water filters to help prolong their life. Silver will not destroy all the harmful protozoa or viruses in contaminated water, and studies have indicated that colloidal silver may be harmful for human if ingested. In 1999, the U.S. Food and Drug Administration (FDA) ruled that colloidal silver products were not considered safe or effective. Some of these products are available over the internet, but I would not recommend their use as a way to purify water.

Hydrogen peroxide. Hydrogen peroxide has been used in industrial and commercial water treatment, but the concentration levels  (35-50%) are much higher than what is available at your local drug store or pharmacy (usually 3%). I have not found any testing that shows this to be a reliable method for the prepper to safely purify water.

Some Final Tips:

Backup redundancy

Because water is so important to your survival, make sure to have several sources of water and multiple ways to purify water.  One filter system may fail, clog-up, get broken, etc. so you want to have other dependable ways to purify your water.

Water to Avoid

Toilet reserve tank. Although the water going into the tank is clean (under normal circumstances), these tanks often have had chemicals added to help sanitize the toilet bowl each time it flushes. You do not want to use any water that has chemicals like these in them. These tanks are also not tightly sealed to prevent contamination from entering. If the tanks are chemical free and the water is needed as a last resort, make sure to further purify it before using.

Radiators. Antifreeze is poisonous. Never use water from your vehicles radiator.

Water beds. Waterbeds usually have chemicals in them to prevent any mold and bacteria from growing inside your mattress that are harmful to drink.

Pools, spas, hot-tubs. Again, these usually have chemicals treating the water which could make you ill.

Flood waters. Flood water is usually highly contaminated with a variety of harmful and dangerous materials. Chemicals, gas, diesel fuel, oil, pesticides, and raw sewage are just a few of the contaminants usually found in these waters.

Salt water. Drinking salt water will cause you to become dehydrated. If you took a few gulps of seawater, your body would have to urinate more water than you drank to get rid of that extra salt, leaving you ever more thirsty.

Transporting water

You will need containers to be able to transport water from your collection point back to your location. Keep in mind that others may be at the same source of water and may not be as prepared as you are. You want to be able to quickly and safely collect the water you need, without drawing attention to yourself. You don’t want someone to take your water or your containers, or to follow you back to your supplies.

Be sure to check out the other articles on this site for more details on these different aspects of preparing your water needs during times of disaster.

Please leave your comments below. I always like to hear your thoughts!

Happy Prepping,


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