Shelter, water, fire and food are required for just about any survival situation. Man-made or delivered by nature, a disaster of major proportions can strike at any time. Shelter is probably the easiest to access of those 4 survival components. Fire may not be an immediate need. And human beings can go days and even weeks without food. But you need water to survive, and lots of it. In most cases, you can’t survive more than 3 days without an adequate supply of emergency water.
Putting aside your requirements for bathing yourself, cooking and washing your survival supplies, let’s talk water consumption. You should know the minimum level of safe drinking water you need on a daily basis to survive. If there are several people in your party, simply multiply by the minimum quantity to understand your needs for an adequate emergency water supply.
The average human body requires anywhere from 2.5 to 3.0 liters (0.66 to 0.79 gallons) of water per day to maintain a minimal level of health. This can change according to the individual, as well as humidity, temperature and climate. For easy math, round that figure up to 4 litres (1 gallon) of water per person, per day, just for drinking.
This is because your body is composed of approximately 65% water. Even if you limit your activities drastically, your body processes water automatically and continually. It needs to be replenished. While most survival situations resolve themselves after about 72 hours, do not plan on that.
Store enough clean drinking water for one week and multiply that times the number of individuals in your party. That means 28 liters or 7 gallons of drinking-only water per person for a one-week survival supply. And remember, these are bare minimums. If you have the means to store more than that, definitely do it.
For sanitation, hygiene and all non-drinking needs, you should figure on storing an additional 2 times that same amount per person. This means that, covering all of your survival needs, your “best case scenario” all-inclusive water supply should equal roughly 84 liters or 21 gallons of water per person per week.
Just remember to date all of your water containers. Health organizations and survivalist communities recommend storing water for no longer than 6 months before you replace it. This of course depends on how the water is bottled or packaged. If you purchase water in sealed containers, the American Red Cross says it is safe to store for drinking and cooking purposes for one year, until the container is opened. Other factors to consider include emergency water filters and emergency water purification products.