Syringe alternative for sawyer Squeeze?

Flip cap from a 700ml SmartWater bottle.

Yep. +1 on the smartwater bottle. Blue nipple cap. Works like a champ.

Been using the same one since last summer, and it's in good shape still. It's a nice, compact alternative to the syringe.
Kelly

Could someone please explain how you use to to back flush then?

Forcefully squeeze clean water into the clean side of the filter. That's it.

Unless you are going to be dealing with murky, silty water you probably won't need to backflush in the field. Do it at home and the filter shouldn't clog from a few days or a week of use.

Yet another +1 for that cap use for back-flushing.

… it also happens to be useful in a gravity feed set-up as the connecting cap for your receiving smartwater bottle (obviously)or your platy.
A feed hose will fit through the opening of the cap with enough compression to prevent leaks.