How Much Water Do We Need to Survive?

by Rob on October 6, 2009

We can only survive about three days without drinking water (as compared with 3 weeks without food) so Water is a crucial part of emergency preparedness.

A few days ago, we looked at the per capita consumption of water in the home as about 25 gallons a day per person… This included drinking, cooking, cleaning, and toilet flushing…

Most water systems in the US are dependent on the electric power grid to operate.  So, no power = no water pretty quickly…

In a survival situation, the bare minimum is 1 gallon per person per day.  This would be used mainly for drinking and cooking.  Cleaning and toilet flushing would need to be curtailed to the least possible usage. 

In an emergency situation, you could possibly need up to 7 days supply.  This is a good start.  So, take the number of people you need to provide for and multiply by 7 and this will give you the number of gallons you need to get by.  Just to be safe, you should probably double this number since it is likely that it will take a few days to really start conserving this precious resource.

As an example, for a family of 5 you would need 35 gallons, and doubling it would give you 70 gallons that you should store.

Storing water in empty 2 liter soda bottle is a great idea because it is portable and relatively earthquake proof. If you needed to “Bug Out” and leave your home, you could bring some water with you as part of your 72 Hour Bag (to be discussed in greater detail soon)…

Places in your house where you can get water– your hot water heater holds usually 40 gallons.  And the tank portion of your toilets has water that can be used for some non-drinking/cooking purposes.  And your downspouts can be a great place to collect water.  1 inch of rain on a 1000 square foot roof = over 699 gallons of fresh water…

Lastly, you can fill up sinks and bathtubs ahead of time if you have any warning that you might lose the water supply.

In future posts, we will discuss how you would prepare to provide an on-going supply of clean drinkable water for your family in a longer-term emergency…

Start filling

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October 6, 2009 at 7:25 pm

{ 23 comments… read them below or add one }

Sneaky Pete October 6, 2009 at 10:06 am

Good start.
Water is heavy, and bulky.
Get a filter system together so you can drink ‘found’ water as well.


Lisa October 6, 2009 at 4:14 pm

Thanks for putting the numbers to it. I remember during the Y2K scare, my fatehr jumped on the band wagon and started purchasing water. I don’t think he put any math to it and just based it more on how many he could fit in the cart.



Lynn Lane October 6, 2009 at 4:44 pm


Yes….water and Ammo! A must :-)

Lynn Lane


Keri Eagan October 6, 2009 at 5:43 pm

You can drink the cistern water as long as you don’t use those tablet things. After one of those is added I’d give it six months of water flowing through before I’d be ok with it. Important to think through how to collect water before you need to do it. Once we are accustomed to turning on a tap we forget how long it would normally resource our own.

Keri Eagan
Anything Alternative


Las Vegas Baby Boomer Dating Expert October 6, 2009 at 7:42 pm

Excellent excellent points. Water being in most cases the most important emergency preparedness item since we cannot go without if for long.

I’ve convinced my sis that we need to have 3-7 days worth of drinking water stored. Californians are used to discussing earthquake preparedness. Las Vegans, well, we want to horde water anyway because of the desert heat. We likely need more.

Looking forward to your further developments here.

Happy Dating and Relationships,

April Braswell

Single Baby Boomer Dating Success Expert


Martin October 6, 2009 at 7:55 pm

Unless the apocalypse changes the weather system (which it could do), all we need in the UK is a few buckets to catch the rain and maybe some water purification tablets.


Jose Escalante October 6, 2009 at 8:07 pm

This is perfect. I now have a clear plan of how much water I need to store in case of an emergency.

Jose Escalante


Lisa McLellan October 6, 2009 at 9:21 pm

We take our running water for granted. Anytime we have had to shut the water off in the house for a repair etc. I still turn on the faucet at least 50 times during the day forgetting that it won’t work.

I checked under the bed Rob, to see if I had room to store anything. There’s already a bin of lingerie under there! I guess I could dump that, because in an emergency situation – it won’t do any of us any good – none of it is built for comfort or warmth!!! lol

Lisa McLellan
Babysitting Services – Babysitters and Nannies


Martin O'Connor October 6, 2009 at 9:29 pm

I’m thirsty for more.

Martin O’Connor


Jennifer Battaglino October 6, 2009 at 10:40 pm

I’m filling! I’m filling! Any websites that you would recommend that are legit to get the supplies you discuss?

Jen B

The Harwood Center – Tinnitus, Chronic Illness, Fears, and Anxiety


Katie October 6, 2009 at 11:49 pm

When the water is gone, I turn to wine. Couldn’t resist. In all seriousness, 7 gallons per person is not as crazy trying to store 25 gallons/day per person. I like this.



Kate McKeon October 7, 2009 at 12:45 am

No doubt storing 7 gallons per person is a managable goal. I remember stocking up on water a few times with my Dad in Berkeley. You never knew when a big earthquake might hit so you had to be prepared.

To this day I keep canned goods in my pantry – foods I don’t even eat – just in case. I figured out the protein/carb/fat ratio that would allow me to survive and reduce my metabolism (by eating less – calorie restriction) so I’d need less to survive.

Not fun to think about, but better to consider in advance!



Steve Chambers October 7, 2009 at 12:51 am

Water is the most critical element for survival in the short to medium term. Great advice for storing and finding the necessary supplies.

Steve Chambers
Sales Training Speaker


Vicki October 7, 2009 at 1:23 am

We have a well were we can hand pump water which is a big plus in time of need. I think 7 gallons is a good start/reserve. It would be the first thing I would stock if we didn’t have a well though. The thought of saving rain water from roofs for showering ect. would be a must to make supplies last longer.



John Ho October 7, 2009 at 7:51 am

When the Y2K bug was near abck in late 1999, I bought a decent water filter that was used by Red Cross internationally where water quaility was dubious in war torn areas. We had a swimming pool with about 50,000 litres. So I feel safe that if needed be, I could filter the water for drinking purpose.

John Ho
Numerology Expert Helps Understanding Personality for Better Influence & Persuasion


Robert Martin October 7, 2009 at 11:13 am

I like the 7 gallons ideas. I can work with that.

Robert Martin


David Power October 7, 2009 at 2:19 pm

Im with Rob Martn, I love the idea of the 7 gallons of water…!


Stan Leam October 7, 2009 at 6:51 pm

Right on Rob. I bought a Berkey light a few months back for this very reason. Everyone should have some sort of off the grid water filter system accessible to them in times of crisis.


Darryl Pace October 9, 2009 at 5:54 pm
Mag December 23, 2011 at 12:16 am

great article. For the past several years whenever I buy soda I always fill the empty with water. We have 2 people in the house plus 2 dogs and they would need water too. At last count I think I have well over a hundred gallons stored…being in LA I know an earthquake will hit at some point. In this day and age who knows what else could happen. In addition I have an emergency kit with plenty of medical supplies, pain killers,antibiotics,masks,gloves etc. You can’t be to careful.


Al January 16, 2012 at 11:49 am

Did you know that water weighs 8.35lbs per gallon? Let’s round up to 8 1/2 lbs to include the container it’s in. So for your family of 5 storing 35 gal of water means 297.5lbs in just water alone! if you store 70 gal it’s 595lbs of water!!! If you’re plan is to bug out storing lots of water isn’t feasible, because you won’t take it all with you. It might be better to have a hikers filtration bottle w/ replacement filters or iodine drops. But if your plan is to bug in this is possible. Just something to keep in mind.


mii February 7, 2012 at 6:48 pm

this does not really answer my question of “how much water do we need to survive? “


JT April 20, 2012 at 11:51 am

A gallon per person per day. So I guess to survive a week, that would be 7 gallons (for one person). To survive a month, that would be roughly 30 gallons (depending on the month – maybe 31 gallons, maybe 28 gallons). To survive a year, that would be 365 gallons. So depending on how many years you plan to survive, multiply the number of years by 365. For example, if you plan to survive 20 years that would be 20 x 365= 7,300 gallons. And we wonder why Americans are viewed as idiots. I am sure that you do not drink a gallon of water per day. However, we are wasteful and do not realize how fast that gallon will be gone. Surviving includes washing and cooking. If you can tell us all a way to survive without cooking and washing, by all means bless us with your knowledge. I would love for you to survive without bathing once in 20 years. That is a great way to avoid ever getting laid. And if surviving means no sex, I’d rather die. I am sure that some cooking can be done without water. However, I am guessing that if you are interested in survival, you will also be saving foods that have a long shelf life. These items include MRE’s and freeze dried foods. While MRE’s can be eaten cold, it would be nice to cook them on occasion. If you are cooking, you will need to wash the dishes used or use the included heater which requires (yep you guessed it) WATER. Freeze dried foods require water. Learn to think for yourself. A gallon per person per day. Not too complicated.


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