I like the Katadyn Units and I did a cost comparison btw the units and this is what I came out with:
I like the Katadyn units and this is what I figured out in my research and price comparison. These are the units I looked into:
1. Katadyn Pocket(up to 13,000gal before filter change) MSRP $370 and Filter MSRP $200.
Katadyn Pocket video
2. Katadyn Mini(up to 1,850gal before filter change) MSRP $110 and Filter MSRP $60.
3. Katadyn Hiker Pro(up to 300gal before filter change) MSRP $85 and Filter MSRP $50.
4. Katadyn Hiker (up to 200gal before filter change) MSRP $70 and Filter MSRP $50.
Those were the models that I had to choose from and this is how I chose the model that I did.
1. The hiker was a GREAT price at $70 but it only lasted 200gal compared to the pocket which is 13,000gal. So I would need 65 filter to last the length of the pocket which would cost me $3250.
2. Next was the hiker pro which is a step up from the hiker and can connect directly to a hydration system like a camelbak which I like but only last 300gal before a filter change and compared to the pocket that is 43 filter and that would cost me $2150.
3. Now the Mini which is nice and light and small for packing which is a plus and the filter last 1,850gal. But it would take too long for 2 people to use and I would need 7 filter to last as 1 pocket for a cost of $420 which is not too bad.
4. And not for the one I choose the Pocket. It last up too 13,000gal and comes with a “LIFETIME WARRANTY” so if it ever does happen to break they will fix it for free and it is very solid. Now for the cons on this one. It is a little larger than some and weight a little more at 10″ high and 20oz. A MSRP of $370 and for the filter is is MSRP $200.
I choose the pocket because it will last probably a lifetime for me before I had to change the filter

I could use it in a nice mountain stream or in a pond with out a problem. It does cost a bit more in the beginning but I will have to change the filters as much. The other filters will work great but the dirtier the water the less gal you will get out of the filter.