Hydro Photon Water Bottle Pre-Filter - 2008 BCS

Really easy and efficient way to get the sand and other particulates out of your water. Just twist it on your nalgene, dunk it in the water, and then Steripen the water. I have the Adventurer Opti steripen, so I have to take the pre-filter off to use the Steripen, but if you have the models that nest into the pre-filter, all you have to do is pop off the filter screen and insert the steripen. HydroPhoton says the pre-filter forms an air tight seals with the groves on the nalgene, eliminating the need to worry about unpurified water on the rim of the water bottle. To be safe I always give it a wipe down, and then once I've purified the water, I turn my bottle upside down with the cap just barely on to rinse watevers left with clean water.

Highly recommended if you are using the Steripen system to filter your water. For 12$ and no extra weight, it makes sense to get this.

Friend and I used this for a week long trip to the Boundary Waters. I didn't know before hand that my generic-brand Lexan bottle wouldn't have the same threads on this screw-cap prefilter. Luckily my friend had a Nalgene bottle, and we had no problems. It filtered out debris, but not the color of the water. Not a problem for us, but beware to those who have a problem believing brown water is safe to drink after you've used the pre-filter with the Steri-Pen.

Just because you have a Steripen doesnt mean you will have clean-debris free water. This filter is essential, in fact it should come with the Steripen standard (that crucial). It screws on top of your wide mouth Nalgene bottle as you dip it into a stream lake etc... and the nasty silt sand etc... get stuck outside the filter and not inside the water you are about to zap with UVC light. Then as the water bottle is filled with untreated water pull out the mouthpiece portion while leaving the filter screwed into the Nalgene and add the Steripen then turn the Nalgene upside down and rotate for 90 seconds and blam fresh water without debris and killed microorganisms. The one thing this and the Steripen do not do is eliminate color from the water. So hopefully that dosent bother you, but most streams and lakes you get pretty clear water anyway.

I used this on a river kayak camping trip with a group of friends. It works great, attached perfectly to an old water bottle that I use.
Friends were a little skeptical about the whole filter and steripen process but everyone survived and they were able to party on with no ill effects!
I'm thinking it would be a great addition to a grab and go pack.