Denver’s running out of water.  The latest batch of tornados through the plains states has left many without water.  Long range climate predictions look dire, and already, some of our sources in southern India are reporting temperatures of 128º F are coming this summer.

OK, alarming enough, you might say, but is it really necessary to do anything about it?  We think it is.

To recap, there are a large number of potential threats to your personal independence entangled in the water question:

  • Short term, you can’t survive more than a few days without water.

  • Perhaps because of global warming, drought is spreading in the U.S. (and elsewhere)

  • Terrorists are known to have at least discussed the possibility of attacking our water sources.

  • Freak weather, perhaps increasing due to climate change, may wreck local water availability.

  • Random non-violent events, such as accidental utility crew dig-up accidents, may leave you without water.

  • Long term, water may prove as valuable as oil.

The Short Term Plans:

If your city water supply was shut off today, you would have several days of water in your home, provided you have not polluted it yourself. 


One specific danger to home water survival plans are those toilet bowl fresheners that live in the fresh water holding tank of your toilet.  No matter how ugly the inside of a toilet tank may look, the water is perfectly drinkable.  There’s at least one gallon per toilet in your home.  That is, if you didn’t fall into the corporate-consumerism crap of putting a Tidy Bowl, or other toxic source, in your supply.

Hot Water Tanks:

Virtually all hot water tanks have a flushing valve at the bottom of the tank so you can periodically remove sediment.  The sediment that comes into the tank from your local water source, settles to the bottom, along with flakes of this and that from the heating element. 

You need to make a monthly habit of connecting a drinking water safe hose to the bottom of the tank and flush it until the water runs crystal clear.  If you don’t make it a habit, you’ll find when you do need the water some day that the first 10-20 gallons will be undrinkable due to sediment.  Besides, the tank will last many years longer.

The Ice Maker:

Around our house, we leave the icemaker on all the time in order to keep ice handy.  It’s useful for drinks, cooling off hot coffee in a hurry, and if you think about it, it’s a handy way to have a gallon or two of water that you might otherwise not think about. 

Rain Barrels:

Although they are out of fashion in suburban America, you can easily pick up a large barrel made of plastic (the kind bulk food supplies come in) or if you want the ultimate, you can buy those barrels that are used for bulk foods in stores for about $115 each.  See:

Our preference is a regular garbage can type, with a cover, so that you can effectively seal the water in once you’ve collected it.  A little bit of childs modeling clay makes a non-toxic seal around the downspout, which can be cut off so it just fits the barrel.  If you want to get real fancy, you could pick up a plastic valve at Home Depot and put in a bottom drain, just like the hot water tank, but it’s easy just to empty the barrel on the lawn, hose it out, and let the next rain refill it with fresh water.

Rain barrel water may not be ideal drinking water, especially depending on where you live, and what your roof is made of, but at a minimum it might serve for cooking and some basic washing, not to mention making a wonder rinse for your hair compared with the fluoride and chlorine laced liquid that issues from your shower head.

Big Blue Tarp:

In a real emergency, we don’t see anything wrong with having one (or more) good sized blue tarps, and some extra large garbage bags to be fresh-water liners for garbage cans.  A couple of hanks of rope, some trees, or the side of a building, and you can easily put together a 20 foot by 30 foot rain catchment.

How Much Water?

We can do a little math here and figure out how much rainwater you should be able to collect in the right conditions.  Let’s suppose you have a modest 2000 square foot house and you have positioned catchment barrels.  Let’s also assume that you have augmented this with a 600 square foot tarp setup

Now a little science is brought to play.  Assume exactly one inch of rain is going to fall in the next two days.  How much water would your rain barrel and blue tarp set up capture?

Yield of the Tarp:

  • One gallon is equal to 231 cubic inches.

  • Each square foot of tarp will capture 144 cubic inches of rain when it rains one inch.

  • Therefore, 600 square feet of tarp will capture (600 X 144) 86,400 cubic inches of water.

  • Cubic inches of water (86,400) divided by 231 (cubic inches per gallon) is 374 gallons of water. 

  • That’s almost 7 55 gallon drums worth of water!

Roof Yield:

  • The roof is 2000 square feet.  With one inch of rain:

  • 2000 times 144 cubic inches, or 288,000 cubic inches of rain is collected.

  • 288,000 cubic inches divided by 231 cubic inches per gallon means 1,246 gallons is collected.

  • If you’re filling 55 gallon drums (with super-large lawn bag liners, of course) that would be more than 22.5 drums worth.

Combined Results:

The rain has stopped and we find ourselves the proud owners of 1,246 gallons from the roof, and 374 gallons from the tarp. That’s a total of 1,620 gallons.

If you have a family of four, and you provision one gallon of water per person daily, that is one years worth of water.  At a generous ten gallons per person per day, that’s 40 days worth. 

You’d of course want to put some regular household bleach in your catch to kill the unavoidable critters that live on roofs.  We keep a gallon on hand at all times.  You’d want to have a roof made of copper or glazed tile, too, if sanitation is critical. 


These numbers are theoretical.  The odds of the water in your house going off long enough to force you to drinking from the icemaker, the toilet, then from the hot water tank are really small.  But, it’s also not zero.

With a tarp, some hooks, some rope, and a package or two of extra large garbage bags to line garbage cans, you can have plenty of water no matter what happens.

It also gives great meaning to the idea of keeping your gutters spotlessly clean and the downspouts clear.

Long Term:

For now, Independence Journal is published in Boca Raton, Florida, where we’re pleased to report, 20 inches of rain is normal for the first five months of the year.  While we have made a conscious decision to buy water and sewerage from the City of Boca, we are also aware that with a little work on the gutters, we could have collected 32,400 gallons if we had to.

Because we lived on our sailboat previously, we also know that two gallons per person is more than ample if you’re on tight water rations.  We just don’t think our neighbors would appreciate the 589 55-gallon barrels that would cover everything in sight if we opted to collect this much!

More seriously:  As the lead article about Denver shows, rainwater catchment is not a popular way to live.  Still, if you have a roof, a tarp, and some ingenuity, you can afford to achieve a greater level of independence than most.

From a career and life planning standpoint, we would strongly suggest that you consciously look at the long term drought forecasts from the U.S. Department of Agriculture before taking that “high paying job in Denver” – the real returns may not be at first apparent.


(2004) Home-Spun Water — No Comments

Leave a Reply

Your email address will not be published. Required fields are marked *