ATO for RO DI?

[rhodan]

I have nice little setup to top off my tank but the fresh water source tank has to be refilled from time to time as well with RO water. Is there a system or a DIY system that turns on the RO water once the level gets to low? Right now it a manual process to turn the water on and wait a few hours for the trash can to fill up and then turn the water off. But if I forget and I have in the past, big time mess.