I had a float valve with my original kit but it only stopped the pure water from the RO. It didn't stop the waste water. I just time it now and use a barrel as an overflow tank in clear view of my back door a bit like the expansion tank for a car radiator. If there's any water in it I know my main tank is full and I turn everything off and switch the barrel for an empty one. I also produce my water in my garden in a small cabin.