o.k. I am confused about RO systems.

let me see if I've got it straight or not. you connect the r.o. unit to a
faucet or water source. from that you will have one hose running into a
receptacle and another running into a waste receptacle. You ??have to have
your water running 24 -7?? or else the life span of your filter is going to
decrease significantly. How much are filters anyway? and how often do they
need to be replaced on average? What do you do if you go away for a few
days (whose got room to house a receptacle that will hold 3 days of water)
or if you just don't feel like changing water that on a military schedule.
Furthermore it seems like these things waste a horrendous amount of h2o? I
keep discus and don't like how my tap water fluctuates.
I see that a lot of people use R.O. systems but it seems like
waaaaaaayyyyyyy to much trouble. I have got to be missing out on something.
There has got to be some tricks associated with these to make them easier.
I mean I am all for the labor of love but man! Please tell me that I have
got something wrong or am missing out on somthing? I like the idea of pure
h2o to work with but am not rich by any means, and also like to enjoy my
fish more than fooling with plumbing.

also if anyone has come up with a better way to do water changes I am sure
we'd all like to hear about them.

Ben C