In my reading about water purification one of the things that I read about was ultraviolet (UV) light purification. I discarded it because I live at a fairly high northern latitude (lower intensity light) and it is fairly cold here most of the year. I just noticed something though. Sitting next to me I have a “halogen gooseneck desk lamp” with a 20 Watt halogen JCD bulb in it. While looking at the glass piece that sits between the light and outside world I noticed that it says “UV Filter 001”. This got me to wondering how much UV light this bulb is throwing off, and if it could be used for water purification (assuming power is present and water is down or contaminated). I wasn’t able to find much info on UV output of halogen bulbs, other then G.E. claims that their bulbs put out very low amounts of UV.
Near the bottom of this page I did find a nice set of tables talking about how much UV is needed to kill various micro-organisms. – Ben
JWR Replies: To sterilize water, it is best to use a light bulb that is optimized for transmitting the UV portion of the light spectrum. As koi fish fanciers discovered a decade ago, UV light does a great job of sterilizing water.It actually does not kill all the bacteria, but it renders them harmless by making them incapable of reproduction. (Typically, folks with koi ponds use a water pump to circulate water in conjunction with a UV light that shines on a clear plexiglas section of water pipe, gradually treating all of the water in the pond.
On a smaller scale, the same technology is used with the SteriPen device made for backpackers. (SteriPens are available from SafeCastle, Ready Made Resources, and many other Internet vendors.)