I have the same problem. Before I moved, I had a Kent Maxxim RO/DI system in my laundry room that was connected to a 20gal garbage can. I still had to haul buckets to my tank for top-offs. When I moved into my condo, I knew that I would not have enough room for a garbage can to hold the water, particularly since the RO/DI unit was going to be installed in the kitchen. I also knew that I would NOT be able to connect the RO/DI system directly to the tank since the tank is not near a water source, I have hardwood floors, and concrete ceilings. This is what I did.
1) I replaced the membrane with a 100 gpd unit for faster top-offs.
2) I added a drinking water kit. The kit includes a faucet that mounts to the top of the sink, and a 4 gal. bladder tank to store the water. I upgraded to a 10 gal. bladder tank, which was the biggested that would fit inside the cabinet next to the sink. I drilled a hole through the cabinets to run the 1/4" water lines between the RO/DI unit (under the sink) and the bladder tank.
3) I added an on/off valve with a quick-disconnect to the output from the DI unit. When I need to top off the tank, I run a 1/4" water line from the valve to the tank. I added a Kent float valve to the sump so that I won't over-fill the sump. I should only need to hook up this line every couple of days for top-offs. The 10 gal bladder tank should hold enough to top-off the tank in a few minutes. I can also leave this line connected if I am gone for the weekend so as to have automatic top-offs.
A few other thoughts, if you have a closet near your tank, you can hide a large baldder tank (they make them in all sizes) in it and have the bladder tank hooked-up to your sump for automatic top-offs (sort of like a Nurse system). Depending on the size of the bladder tank and your evaporation rate, you might only have to re-fill the bladder tank every couple of weeks.
BTW, Aqutic Reef Systems helped me tremendously with the system lay-out and supplied all the parts.
Mike
