My northern Nordic peers will probably be less interested in this, benefitting as they do from the pristine waters of Lapland, but my search for the perfect filter is finally at an end.
When I arrived in the States, one of the first things I had to deal with was the need to filter all the water found in the wilderness. There are several methods to do this - chemical tablets, pumping through a filter, boiling, or combinations of the above.
I was advised in one shop to purchase an MSW Sweetwater filter, which I diligently did, only to find after two or three days it had clogged with all the slimy water up in the Minnesotan northwoods. It kept me giardia-free, but man, the pump was annoying. It has a pressure-release valve that squirts out dirty water when the filter gets clogged, after which you are supposed to clean it. I cleaned and cleaned, to no avail. Pumping water became a chore I wouldn't wish on anyone.
So my search began for an alternative. On Backpacking Light the promote the Frontier Pro, which claims to filter out >99.99% of all evil-doers. However, popular opinion seems to indicate that water filtered through it requires pre-treatment with either household bleach or purification tabs. This seemed an additional step which I couldn't be bothered with.
In addition, the Frontier Pro only filters about 50 gallons of water safely, after which you need a new one.
The nice thing about it, however, is that it is adaptable; it can be attached directly to a 'dirty' bottle, and filtered water can be drunk through a bite valve. Or it can be attached inline and used in a gravity feed mode. Nice. Jason Klaas has a good video explaining everything. And only 1.97 oz (56g) compared to the 11oz (320g) of the Sweetwater.
I ordered one - and then found out that my local REI had the Sawyer filter.
The Sawyer is also an inline filter, but it has a couple of key differences: It filters everything except viruses, so no pre-treatment of water is required. Secondly it is guaranteed for a million gallons - significantly more than the Frontier Pro. The design draws on the same process behind dialysis machines, so it's proven effective. And it only costs $55.
The nice thing about the Sawyer is that it can be used in three different ways.
1. Inline, with a dirty platy feeding, and a hydration tube on the outflow. Just attach the tubes, fill a platy with dirty water, and drink straight form the pack, hydration bladder style.
2. Gravity feed. Hang a dirty bag and let it drip through the filter into your clean bottles or platys. I used this method in the Porkies as there were two of us (as seen below). The drip flow is very fast - about a litre a minute.
3. In Bottle. The version I bought came with a bottle inside which you can attach the filter to the lid. Then you simply fill the bottle with water, and suck up the filtered, clean water through the straw. This would be perfect for a UL solo trip.
You're really spoiled for choice.
In practice I found it to be excellent - fast, effective, and hassle free.
If I could locate the problems with the system we used, it would be with the platys. The small opening of the Platypus bottles makes them very difficult to fill from flowing streams or pools. The lack of air in the platys means there is no space for the water to fill. Filling the dirty platy was the slowest part of the process. Once it was done and hung on a branch or hook, clean water began flowing almost instantly.
I made a few MYOG adaptors to make switching tubes easier. Platypus has a 'quick-connect' system which I've fitted to a short outlet tube. This allows me to plug in a hydration tube when in the pack, or a short bottle filling tube when used in gravity feed mode.
I found it is also possible to connect a hydration tube bite valve directly to the outlet nozzle instead of fitting the tubing tightly over it. This makes for a very fast, adaptable system. I'll try and post some pictures when I get a chance to show you what I mean.
Cleaning the filter is easy. A faucet/tap adaptor is supplied in the box which you attach to the outlet in order to backflush the unit. Simple.
All in all then, I'm very happy. It's so nice to just sit and watch the filter doing it's job instead of getting aggravated by the irritating pump. It weighs next to nothing - about 2 oz dry - and is very flexible. I look forward to trying it out again in a different configuration on a solo trip.
Now, does anybody want a MSR Sweetwater pump?