[gordons]

Hi there i have been looking at wfps can anyone tell me what you put into a backpack wfp, is it just normal tap water or is there a special thing you have to put in

[pjulk]

Back packs like any other WFP sytem need purified water, Tap water would leave the windows in a right me.
So you will still need at the very least a DI filter and if you live in a hard water area you would need an RO filter other wise it would cost a fortune in resin.
You will also need some thing to store the water in after purify it.

Paul