One of the most pressing needs for human survival is adequate drinking water. By adequate I mean sufficiently abundant and sufficiently pure. The definition of "sufficiently abundant" changes depending on environmental conditions of temperature and humidity, individual activity level, conditions of health, age, body size, and other factors. In a survival scenario, where conditions are more demanding, the need for water intake increases. I recommend planning on one gallon per person per day for drinking and food preparation — and that doesn't take into account the need for water to handle sanitation issues.
Insofar as water is concerned, our bodies are like car engines that are never turned off, but are left running all the time. Unless the fuel supply is replaced, eventually the tank runs dry and the engine quits. Extending that analogy to our bodies, even in our sleep the engine is running. The metablolism that keeps our cells alive involves processing water through every cell 24/7, so there's no such thing as shutting down the need for constant water intake.
The challenge comes when we try to keep enough water on hand to supply our needs in the event that some kind of catastrophe shuts down the "normal" water supply. To prepare a method of suppling our own water needs when the domestic supply is unavailable, there are only so many solutions.
One is to have a well on your property, along with the means of raising the water from the depths of the well to the surface — a pump — and the means to keep that pump running: an electric power generator or some mechanical method. That might work for those who live in an area where drilling a well is possible, but that doesn't apply to the vast majority of folks in this country. And even if you have a well, it might go dry in drought years, or if an earthquake causes a shift in the subterranean supply. So wells are not totally infallible.
A few lucky people live near some kind of surface freshwater supply — a river, lake, pond, etc. If you're one of those, you might be able to capture sufficient water and then purify it for your use. If you live in a big city and expect to collect water from the pond in the city park, you'll find yourself competing with other folks and probably dealing with seriously contaminated water from pesticides and industrial pollutants. So factor all that in.
Another solution is to simply store water by utilizing containers ranging from 1-gallon plastic bottles to 55-gallon barrels. Freshwater weighs in the neighborhood of 8.4 pounds per gallon, so the small containers are easier to deal with than larger ones. And if you live in an apartment or condo, where you don't have any property on which to store such items, you'll have to use the smaller containers, storing them in a closet or under the bed, etc.
For those who have the ability to store larger quantities of water in 55-gallon drums, the issue of keeping that much water "fresh" over the long term comes into play. Some people I know dump their barrels every six months and refill with new water. That's not only a pain in the neck, but it can be a huge waste of water unless you are able to make use of it as it's discarded.
I recently learned about a product that makes it unnecessary to recycle the stored water so often. It's called Water Preserver Concentrate (#2C) and is available from a company called QuakeKare (www.quakekare.com). For $11.95 you can buy a proprietary formula of stabilized, ph-balanced sodium hypochlorite that is designed especially to treat a 55-barrel drum full of stored water. The company claims that this product has been tested for 10 years and is registered and licensed by fenderal an state EPA. The company guarantees effectiveness against bacteria, virus, mold and fungus for a 5-year period.
I wanted to let you know about it in the event that it will be useful for your water storage system.