How much water is enough for survival?

by Tom Sciacca

If you like food as much as I do, it’s hard to imagine that our body can actually go weeks without food. It wouldn’t be fun, of course, but it can be done. But without water, our bodies can get into serious trouble quickly – just a matter of days before dehydration can set in. So why is it that many people keep lots of extra food stored in their houses, but neglect to store any water?


This subject came to mind recently when my cousin told me about having to endure a power outage with no drinkable water. Since power outages often impact water treatment facilities, tap water can be unsafe for drinking. The situation was made worse by the fact that her child had vomiting and diarrhea, which meant that there was an even greater need for drinking water, as well as water for cleaning, sanitation and hand washing.


For instance, a mixture of water and chlorine bleach would have greatly assisted in sanitizing around her child, helping to ensure that others didn’t also get sick. And obviously, you wouldn’t want to clean up after such a mess without being able to thoroughly wash your hands. (As a dad, I know that’s NOT fun!) Finally, water for food preparation is a supply you’ll need over and above what you plan to drink.


Now if you look at the conventional wisdom out on the internet, you’ll find guidelines such as the following:

  • A normally active person needs to drink at least a half gallon of water every day. Hot environments can double that, and children, nursing mothers and ill people will need even more.
  • Additional water should be stored for use in food preparation and hygiene.
  • Store at least one gallon of water per person, per day. You should have at least a two week supply of water for each member of your household.


This is all well and good for the most basic needs, but I recently contacted a very knowledgeable ecologist and cultural anthropologist about her opinion of these recommendations, and she recommended much more. Back in the times when people hauled water from lakes and wells, she told me, a normal household used over 2 gallons of water per person for cooking, cleaning and drinking. Nowadays, people are so accustomed to having plenty of fresh water around that it’s used at a much higher rate. (Don’t forget that people only bathed once a week in olden times!)


So my latest philosophy is that it is better to plan on 2-4 gallons per person per day. Sure, you may use less, but what if the situation lasts longer than you planned? You’ll be happy you had the additional safety margin.


Now, where should you get the water? Well, for a while, I sold canned water, as it can be stored easily for long periods. But after a time, I began to realize that the shipping cost of canned water made it very expensive for customers to acquire (plus, it’s not exactly a “green” practice to ship water that you can get from the tap), so now I just give advice on how to store it on your own.


  • You can buy jugs of bottled water or you can fill up old milk jugs (which you’ve thoroughly cleaned, of course). Make sure it’s a plastic that is safe for food use and don’t use them for an eternity. (I’ll cover safe water storage later.)
  • Store the water in a cool dark place, such as your basement, if you have one.
  • Rotate your water ever six months or so, by using up what you have in your cooking, washing or even flushing the toilet, then replenish the supply.


Keeping water on hand is not simply a preparation for TEOTWAWKI, but a smart precaution against power outages, storms or any other time we lose basic services. It means you’ll be less likely to panic (like all those unprepared people) and less likely to be demanding assistance from already-overtaxed emergency services.


Of course, having an adequate supply of food is important too, but without water, you’ll be majorly uncomfortable in an awful hurry. Fortunately for my cousin, she and her family came through okay, but the anxiety she felt during the situation helped her recognize that you can never have too much water on hand.


In a follow up to this blog, we’ll talk about what types of containers are safe to store water in and how to make sure bacteria growth doesn’t ruin your day. See you then!




Tom Sciacca is President of, specializing in wilderness and urban survival.

20 survival items ebook cover
Like what you read?

Then you're gonna love my free PDF, 20 common survival items, 20 uncommon survival uses for each. That's 400 total uses for these dirt-cheap little items!

Just enter your primary e-mail below to get your link:

We will not spam you.

2 thoughts on “How much water is enough for survival?”

  1. I studied this a few years ago. I find the experts do not agree on how much water is required for individuals. I settled on an equation that calculated the water required based on body weight, and level of work. The primary reason was this created the largest volume of water per person.

    I also came to the concluse that the geographic location was important also. Here in Texas, 100 days without rain is not all that unusual. The temperature and humidity were also factors that I used to assume a evaporation rate.

    You may be able to come up with lesser requirements if you live in a location that gets more rain. But, I’d suspect biological issues will require you to have just about as much storage capacity as I do, because you will need to cycle your water to keep harmful ‘bugs’ from accumulating.

    Water is a requirement that you should plan very very carefully.

  2. I live on a VERY large pond that’s utilized by my development for landscaping irrigation and aesthetics. This water feeds mostly from a good-sized local drainage ditch. It’s clean enough for fish, and plenty of kids swim in it without any apparent negative effects, but I doubt its safety as drinking water. Because of its source, I suspect it contains agricultural and road runoff.

    I’m curious what steps would need to be taken to make it potable. I don’t think something as simple as a slow sand filter would get pesticides out. Obviously, the standard boil would only concentrate the chemicals. Would quality charcoal filters work? Would I need to actually distill the water to ensure it’s safety? Anybody out there have any knowledge to share on this? I have a virtually unlimited source of water if I know how to treat it.


Leave a Comment