Letter Re: Making Swimming Pool Water Potable?

Dear Jim:
When I teach classes on water storage and preservation I am often asked this question. I usually respond with a few questions of my own:

1.) Name all of the reasons you need water?

2.) Tell me what percentage each of those requires?, and:

3.) How many of those could you do with pool water just the way it is?

The truth of the matter is that the only reason you would need to “purify” pool water is for drinking or cooking. Washing, (dishes, clothes or bodies) doesn’t  require any pool water purification. Same with flushing the toilet an often forgotten water usage) In longer term “grid down” situations drinking and cooking become a smaller percentage of the water that you would use. If the water is only off for three to four days, you can go without washing clothes or bodies, but there is a need for cooking and drinking. Conversely the longer the water outage lasted the need to use greater amounts of water for cleaning would be required. 

More directly to the inquirers question of how to “Make pool water potable” especially in Arizona the answer is relatively simple: a solar still. A solar still is a simple apparatus that can be made in a pinch with the simplest of items on hand or purpose made in advance of the need. the simplest example is placing a shallow pan with an inch or two of pool water, setting a small cup or jar in the middle, then covering it with a piece of plastic sheeting sealing off the edge of the pan with a rope, bungee cord, or tape and allowing evaporation to do it’s job. The “distilled” water can them collected from the jar. This process doesn’t yield a great deal of water but is very effective.

Option two is by doing a similar thing by placing water in clear two liter bottles and letting them sit in direct sunlight for 6 to 8 hours and letting the sun break down the chlorine (that’s what happens in your pool naturally)  The bottle need to be well sealed and clear.

The third option is making a purpose built solar still. The concept is the same as the plastic covered pan, but on a much larger scale. To produce the two to three gallons a day needed for drinking purposes, a solar still would need to be at least 4′ x 8′. There are plenty of plans available on the Internet, but my favorite plan comes right from the inquirers back yard from the University of Arizona. You can read all the information of effectiveness of materials, water outputs, as well as, construction variants.

As the name implies, to have a solar still you need to have sunshine. In the winter time or If you live in more Northern climes the output of your solar still will be diminished, maybe even to the point of being less than useful. Since I live in the Southwest this is a viable option for me and I am planning on making one of these stills for my families use in the future. – Kory Mikesell