Hi. I dunno how much time the water from my WC kit lasts, CM says that longs 2 years, some ppl said that lasts 6 months......I just wanna be prepared when the water runs out. I cannot buy it 'cause I don't find a reseller that sells it, so I googled and find that It can be done by ourselfes, but I dunno how. can you adviceme me here please???