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Did you know that solar radiation from the sun can purify water and make it safe for drinking from harmful bacteria?
While so often we hear or read about the bad things that the sun is capable of doing to us, we should also know that some of the same energy from the sun can be harnessed for doing good. A few good examples include solar electric panels, solar hot water panels, and solar ovens.
Well here is one more good example. Harnessing the solar energy from the sun to purify water from a lake or stream into safe drinking water. It is much simpler than you may think. Here’s how…
UV-A rays from the sun, (Ultraviolet-A, longwave, 315-400 nm), will terminate harmful bacteria, parasites, and viruses in water, given enough sun exposure.
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 3 liters. UV-A will lose 50 percent effectiveness at a depth of 10 mm in moderately cloudy water, 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 must be a clear plastic bottle. Not glass (glass blocks too much of the UV-A for this purpose).
The bottle must be clean. Common Sense.
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 same angle up to the sun to maximize the UV-A penetration.
Even better would be to 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 time. 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. It is true that the hotter the water temperature inside the bottle, the faster the process, however there is no need to be concerned about temperature provided the water has been exposed to sunlight for 6 hours.
See how easy it is?
If you enjoyed this post, or topics of preparedness, consider subscribing to our survival blog RSS feed or Email notification of new posts on the Modern Survival Blog
Modern Survival Blog
A Survival Prep Must Have For H2O
Posted on Thu, 21 Oct 2010 19:55:26 +0000 at http://feedproxy.google.com/~r/ModernSurvivalBlog/~3/wkCun82-LNo/
Comments: http://modernsurvivalblog.com/health/how-to-purify-water-with-sunlight/#comments
Did you know that solar radiation from the sun can purify water and make it safe for drinking from harmful bacteria?
While so often we hear or read about the bad things that the sun is capable of doing to us, we should also know that some of the same energy from the sun can be harnessed for doing good. A few good examples include solar electric panels, solar hot water panels, and solar ovens.
Well here is one more good example. Harnessing the solar energy from the sun to purify water from a lake or stream into safe drinking water. It is much simpler than you may think. Here’s how…
UV-A rays from the sun, (Ultraviolet-A, longwave, 315-400 nm), will terminate harmful bacteria, parasites, and viruses in water, given enough sun exposure.
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 3 liters. UV-A will lose 50 percent effectiveness at a depth of 10 mm in moderately cloudy water, 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 must be a clear plastic bottle. Not glass (glass blocks too much of the UV-A for this purpose).
The bottle must be clean. Common Sense.
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 same angle up to the sun to maximize the UV-A penetration.
Even better would be to 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 time. 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. It is true that the hotter the water temperature inside the bottle, the faster the process, however there is no need to be concerned about temperature provided the water has been exposed to sunlight for 6 hours.
See how easy it is?
If you enjoyed this post, or topics of preparedness, consider subscribing to our survival blog RSS feed or Email notification of new posts on the Modern Survival Blog
Modern Survival Blog
A Survival Prep Must Have For H2O
Posted on Thu, 21 Oct 2010 19:55:26 +0000 at http://feedproxy.google.com/~r/ModernSurvivalBlog/~3/wkCun82-LNo/
Comments: http://modernsurvivalblog.com/health/how-to-purify-water-with-sunlight/#comments