I have my own home made non-pump filter design. It consists of a 6 inch piece of 40mm PVC, a 40mm pipe joint, and a 40 to 20 (?) pipe reducer.

I created a pair of screens, one on the inside of the reducer where it necks down, the other above it resting against the ring inside the pipe joint and held in by the six inch PVC section.

Between the screens I have it packed with activated charcoal. The bottom of the 6 inch top section is packed with cotton batting. This can also be filled to the top with charcoal from a fire if filtering muddy water.

The thing really is simple and costs very little. It can also be recharged in the field with just about anything in place of the cotton batting and charcoal from the fire.

I have a short section of 10 speed bike innertube on the end of the reducer so it fits inside the neck of a canteen.

I keep a 5 liter waterbag wrappd around the outside and held on with rubber bands. Inside I have a bottle of Iodine drops and a film can of 50 mg Ascorbic acid capsules. I stuff my light weight leather gloves in the top as a plug. Mac