Garrett,

The PVC filter I use is my own design and it is very simple. It is made from 20 mm brown PVC water pipe. There are two main sections each about 10 cm long connected with a pipe joint. Between the two sections is a plastic screen. The bottom section has a pipe reducer on the end. This traps another plastic screen sealing off the bottom section. The upper pipe has a wad of synthetic fish filter fluff in the bottom that acts as a pre-filter. The lower section is filled with activated charcoal. In the field I repack this setion with ordinary charcoal from a fire.

To use it you simply pour water into the top and allow it to drain through. It is fairly fast. To aid in getting the filtered water into a canteen I added a short hose of narrow bike innertube to the narrow end of the reducer. This fits inside the neck of the canteen.

The filter is not designed to work on its own but in concert with iodine or other chemical means. It does do a good job clarifying water and making it more palatable. To clean really dirty water you can join several of the lower charcoal filled chambers together to make a long drip filter.

I've used this system for years in both North and South America, filtering the water then treating with Iodine. I have never gotten sick. I have a PUR Explorer but don't often use it as this system is much easier, lighter and costs about $5 to make. It's the kind of low tech option that "sells well" here in Brazil. Mac