# Safe drinking water



## rachilders (Oct 9, 2008)

Wanted to pass on a trick I learned helping Boy Scouts that we have used when camping. If our water becomes contaminated or you are forced to use a source that may be unsafe as drinking water, this is a way to purify your water. It doesn't include fire or electricity and all you need are items found in 99% of homes. 

First, collect the water in a clean container (plastic or glass) and let it sit for about an hour. Using a one or two clean coffee filters, slowly pour the water from the container, thru the filters and into another clean container to remove as many physical contaminants as possible. If you have access to activated charcoal or clean and washed fine (beach) sand, place a 1/4-1/2 inch layer of the material between the filters before pouring the water. Allow to sit for 1/2 hour then pour the water into a clear plastic or glass container, preferably something no larger than an empty 2 liter soda bottle. Now let the water sit in the sun for 6-8 hours. If you have plain chlorine laundry bleach, one drop per quart will aid in killing any harmful bacteria that may be present, though it isn't necessary. Personally, my preference is to use quart or gallon size freezer bags to hold the water. You can carry a lot since they take up literally no space or weight, you know exactly how much water you have, when filled they can be easily stored and finally, the solar/UV purification process is easier and quicker in a flat container vs. round since the sun passes easier through the thinner layer of water.

There are commercial kits available that use this exact some process, but this way is just as effective and uses materials already available that are easier to carry and store.


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## TrinEire (Jul 23, 2012)

Thanks for the tip and the bags do work better. I've seen this done with clear garbage bags, but ziplocks would definitely be easier to manage.


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## kyhoti (Nov 16, 2008)

Keep in mind a few things when using this method: 1) you are using both UV radiation and heat to neutralize (ie kill) bacteria, so convective heat loss is a concern. Make sure that the bottles lay flat at as close to perpendicular to sun's rays as possible to fully expose contents. 2) viruses may survive if you have ANY turbidity in the water, so coffee filters are a must, do not substitute a bandana or t-shirt for this step. The bleach, if available, will be less effective with turbid water as well. 3) This method, if done right, can actually make very hot water; allow time for it to cool before planning to drink, unless you really like hot water! 
Note: as a test, grab your candy or meat thermometer and try this method: lay the 2-liter bottle on the dash or back ledge of your closed vehicle for a few hours vs. laying the bottle on the ground next to the vehicle. See what temperature variation you get, and also note the condition of the bottles before, during and after cooling. Depending on you lat/long, you might be really surprised at "solar power"! If this doesn't start the imagination machine, i don't know what will.


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## forluvofsmoke (Jan 27, 2012)

*Additional info on solar pasteurization of water*

It is very noteworthy that you can use solar heat only, without the added benefit of UVA/UVB radiation, to pasteurize water. 149*F/65*C will destroy all water-borne pathogens in non-turbid, filtered water. If I have the means to do so, I would prefer the use of a controlled process such as this, using known values and simple process controls such as temperature readings, rather than gambling in the hopes that sufficient UVA/UVB radiation was achieved, coupled with unknown water temperature. If very limited resources are available, UV treatment may be your only option, so do not ignore it's usefulness.

Some interesting methods to accomplish solar pasteurization by heating alone, and by UV radiation/heating are found here:
http://solarcooking.org/pasteurization/solarwat.htm

I'm all for KISS methods, but if I can't KNOW through some form of measurement that it is safe to drink, I will look for a way to achieve such a method...just me. A $4 mechanical/analog pocket thermometer is cheap insurance, btw...


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## OldCootHillbilly (Jul 9, 2010)

Yall wanna be carefull usin garbage bags. Many of em be treated with pestacides.


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## Moby76065 (Jul 31, 2012)

Also do not use glass containers.
Glass filters out all UV rays.


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## rachilders (Oct 9, 2008)

FWIW, this is really an "emergency" method and I wouldn't really recommend it for long term/permanent use or if you are dealing with chemical contamination (oil, gasoline or or other toxic chemicals) in your water source. BTW, using a thermometer is a good idea and I recommend a small meat thermometer as it can also be used to test food to see if it's been cooked thoroughly. 150F can be EASILY reached in most places, even during winter. It's also easier when using freezer or similar bags since they will lay flat and allow the sun to do it's job easier. Just place the bag on a dark surface in full sun and let nature do the rest. Here in Texas, I've had containers left in the sun reach 170 degrees or more and seen soda cans explode. Also, leave room for expansion in your plastic bags when filling with water as when they begin to get hot they can rupture if over filled. We have actually cooked eggs using a cast iron pan, some foil and nothing but solar heat. FYI, if you have a reflective surface like foil or a mirror you can increase temps considerably by using it to reflect the sun onto the surface you want to heat. Remember using a lens to start a fire when you were young?


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