At the moment i do my windows trad but im thinking off going wfp for commercial only as i will loose a lot if i do it on my residential. My idea is, i have a small trailer that's sat in the garage doing nothing so i was thinking off buying a back pack and using it with four 25 ltr containers.How much do you think it would cost to get this up and running as i have no wfp equipment also i would need stuff to get pure water. thanks for your help and ideas