Purifying Water with the Sun

I think we can all agree that having access to potable water is a critical component of our disaster planning. Using the SODIS (SOlar water DISinfection) method of purifying water is just one more tool in our toolbox.

For this method, you need to start with reasonably clean water. By that, I mean it should have sediment and debris filtered from it and it should be free of heavy metals and chemicals. Thus, this won’t work on water you get from your swimming pool or hot tub but will work great on lake and river water.

Next, you need a PET bottle. PET stands for polyethylene terephthalate. Yeah, say that three times fast. The plastic bottles should be clear and if you look at the bottom, you should see the familiar three arrow triangle informing you the bottle is recyclable. Inside the triangle, if you see a number 1, that means it is a PET bottle and you’re good to go.

Remove all labels and stickers from the bottle. You want them as clear as possible. Obviously the bottles themselves should be clean inside and out as well. Oh, and make sure you have caps for the bottles.

A great way to reduce the amount of foreign bodies in the water is to pour it into your plastic bottles using a coffee filter and funnel. This will capture all but the very smallest debris.

For the process to work properly, you’ll need about six hours of sunlight. Yeah, this method won’t work well on rainy days. Fill your bottles to the top with water and screw the caps on tight. Then, lay them on their sides in the sun. Ideally, you will be able to place them on a hard, dark surface like a darkly stained table. The idea is that the surface of the table will obviously get hot as the day goes on and this heat will transfer to the water in the bottle. If you can get the temperature of the water to reach 122 degrees F or greater, the time the process takes is reduced considerably to about two-three hours.

What happens is the UV rays from the sun kill off the pathogens. Again, it won’t do anything for chemicals that may be present in the water so keep that in mind. This only works on bacteria and other harmful organisms.

Published by

Jim Cobb

Jim Cobb has been a student of survivalism and emergency preparedness for almost thirty years. As a young child, he drove his parents nuts with stockpiling supplies in the basement every time he heard there was a tornado watch in his area. Of course, being a child, those supplies consisted of his teddy bear, a few blankets and pillows, and random canned goods he grabbed from the kitchen cabinets. Later, he was the first (and likely only) child in his fifth grade class to have bought his very own copy of Life After Doomsday by Bruce Clayton. Today, he is a freelance writer whose work has been published in national magazines such as Boy’s Life and Complete Survivalist Magazine. He is a voracious reader with a keen interest in all stories with post-apocalyptic settings. He maintains the Library at the End of the World blog and is also the Content Director for SurvivalWeekly.com. He currently resides in a fortified bunker in the upper Midwest, accompanied by his lovely wife and their three adolescent Weapons of Mass Destruction. Jim's first book, Prepper's Home Defense, was published late 2012 and his second book, tentatively titled The Prepper's Complete Guide to Disaster Readiness, will be out in mid-2013, both coming from Ulysses Press.

2 thoughts on “Purifying Water with the Sun”

  1. I purposely keep about two dozen 2-liter soda bottles around for this very reason. It’s a good piece of knowledge to have and with all of the soda PET bottles lying around, it could prove quite useful to know.

Leave a Reply

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