I know a lot of people have probably done this one to death but I wanted to come up with a water purification method that doesn't require fiddling with timers, can be expanded easily, and uses automation gates (because I love that stuff). (Ignore the bridge going in, it's a relic from earlier production) Water goes in to reservoir through shut-off. Reservoir doesn't release water due to open mechanized door. Standard. The automation part comes in with a memory toggle. As the tank is filling (to a preset level, I do 4% as it keeps a steady stream of output but it can go to any amount) The toggle is set to allow water through and open door underneath. Once tank hits full it sends a signal to toggle to close door and sends signal to shut shut-off. Buffer gate is set to something around 100 sec (I think it can be lower but you want to make sure the water is purified). Once buffer gate goes red, tank empties until it sends all-clear signal to toggle and shut-off to open back up. (Important note, either the door needs to be powered or the piping from shutoff to tank needs to be 6 or so more length as it's possible for a little dirty water to sneak through the reservoir before the door opens up.) It can be compacted down to essentially the tank/door/shut-off once the chlorine is piped in.