Discussion in 'Cooking & Water Purification' started by Toddg, Jul 30, 2019.
I was actually shocked when it worked!
I've done it. It was for a demonstration but it works if you need to purify water.
Some folks say that it leaches chemicals into the water. I pay that no mind. If I'm in a survival situation and need water, I'll worry about the chemicals later...
We used to do that at scouts using either paper bags or cups.
We needed more than one paper bag but it still worked!
Not in plastic, but paper cups, back in the day......
Agree, to my mind.....if you are in that bad of a spot.....just DRINK!
if you dont, you die....if you do...you "might" get sick a few days from now
Have not done it with plastic. we did it in Scouts using a paper bag.
Heard of it, but never tried it myself.
Milk cartons work good.
Yes u have done that a few times years ago. It deformed the heck out of the bottle and the water tasted funny, but it worked. Should try frying bacon and eggs in a paper sack
Yep, tried that and surprised as well. Worked like a champ.
How does paper work, rock boil?
I’d rather have giardiasis than cancer
have seen it, never tried it,
my question is in survival situation is it worth the risk of damaging your only water container, over the risk of drinking contaminated water?
personally rather wait the 6 hrs and try UV purification
A clear plastic bottle filled with water, exposed to the sun for 6 hours will make the water safe to drink (see the caveat list). In fact, the effectiveness of terminating harmful bacteria is an amazing 5-Nines, that is, 99.999 percent!
List of germs that are terminated from UV-A sunlight exposure at 6 hours
Bacteria – Escherichia coli
Bacteria – Vibrio cholera
Bacteria – Salmonella
Bacteria – Shigella flexneri
Bacteria – Campylobacter jejuni
Bacteria – Yersinia enterocolitica
Virus – Rotavirus
Parasites – Giardia
Parasites – Cryptosporidium (needs 10 hours exposure)
List of caveats to UV-A sunlight water purification
This method kills germs. If the water is already contaminated with chemicals from pollution, the chemicals will remain.
If the water is cloudy and dirty, it should be filtered first to allow the UV-A rays to effectively penetrate into the water.
The plastic water bottle should be no bigger than 2 liters. In moderately cloudy water, UV-A will lose 50 percent effectiveness at a depth of 10 mm (about 0.5 inch), whereas UV-A will only lose 25 percent effectiveness at a depth of 10 mm in clear water. Just use a typical size soda bottle or water bottle.
How to purify water with sunlight
The recommended bottle to use is a “PET” bottle. It is very common and is typically used for soda or other soft drinks.
PET, PolyEthylene Terephthalate, Recycle code #1 on bottom of bottle.
The bottle must not be colored. It must be a clear bottle. Again, it should be a clear plastic bottle. Some types of glass will block too much of the UV-A spectrum for this purpose.
UPDATE: I discovered this during a re-check of SODIS information in 2017:
Different types of glass have different chemical and physical properties. Certain types (e.g., quartz glass) have a very high transmittance for UV radiation, while other types (e.g., window glass) effectively filter out this part of the solar spectrum.
All commercial glass bottles used for beverages that were tested so far at Eawag had a UV transmittance comparable to PET bottles, and were, thus, suitable for SODIS. No differences were found in studies of glass and PET bottles that compared their SODIS effectiveness.
It is possible, however, that certain glass bottles available in target countries have different UV transmittance properties, and we recommend testing UV transmittance of locally available bottles before promoting them widely for SODIS use. Glass bottles also have certain disadvantages compared to PET bottles which include their greater weight and risk of breaking, limited availability in suitable sizes, and the lack of reusable caps.
The bottle must be clean. Common Sense.
Know your water source (as best you can)… if you believe it to be chemically toxic, don’t use it.
Fill the bottle with water. If the water is very cloudy, it must be filtered by first pouring through a cloth or such material to capture sediment.
Lay the bottle down in the sun. Do not stand them up. Ideally the bottles would by placed so that they face the the sun at a similar angle, to maximize the UV-A penetration.
Even better… lie the bottles on a reflective surface to increase the UV-A exposure using direct and reflected sunlight. This is not necessary, however it would shorten the required time and ensure optimum UV-A exposure.
If the sky is partly cloudy with only a few clouds, then 6 hours sunlight exposure will be enough. If the sky is half filled with clouds, or more, then 2 days will be required.
Note that the outdoor temperature does not matter, so long as the UV-A sunlight exposure has been 6 hours.
Did it once. The bottle was brown and not healthy looking. That said if I was in a bad spot I'd do it.
I actually agree completely, i would not risk compromising my only water container. This was done as a "sitting round the fire" experiment.
You could do it that way but you can also sit a paper bag right in the midst of the fire as long as it balances and stays upright. The water in the bag will boil. It will burn the bag to the waterline but below that the bag will remain intact as long as it has water in it, even boiling water.