I agree the steripen works as advertised in clearer waters but in murky or really dirty water you will have to pre filter it. You can use a bandanna, sand grass type filter, commercial filter, or let it stand for a while and let the heavy solids settle to the bottom. Down in Fla, I use a Katadyn combi filter with my steripen to get rid of all the pesticides down here and it also cleans down to .2 micron at a 13000 gallon capacity, then I follow behind it with the steripen. But when I get water out of our springs or clearer lakes, I just use the steripen without the combi. It's all in what you want to do, but I can make a homemade filter out of sand,grass and a bandanna to clear a lot of the murky junk out without the combi but the pesticides still pose problems in a lot of areas.

Here's a old article of them doing research with LED's but I guess they haven't got it to work this many years later.



http://bangordailynews.com/news/t/outdoors.aspx?articleid=104036&zoneid=115

To me that military quote says the SteriPen can be trusted, provided the water is clear.

One concern with this approach is whether there may be water left untreated, eg on the threads or outside of the container you are using.