Auto-filling 55gallon barrel with RO water, best valve?

[sativuhhh]

My undercurrent rwdc is getting close to completion and I was working on my extra water storage barrel. Going to have a RO system run water to the barrel to store up fresh water that will then drain into the top-off res/system. It has the 2 bungs on the top. I can use a manual valve but don't really want to have to keep an eye on it and let it overflow or forget to fill it when it's needed.

Looking around you would think there would be some neat float filler that would screw into the bung fitting and have a float and everything already built in, but I've not been able to see such things. Not sure if I can get a float inside somehow, I guess if i can't use the top it would be best to drill in a float out the top side somehow maybe if I can get one small enough to get into the barrel?

How do you all auto-fill stuff like this?

 

[TorturedSoul]

If you don't receive any replies showing examples, do a web-search for:

float valve for water barrel

I just did and got 8,400,000 results. There appear to be LOTS of products/solutions for this.

 

[sativuhhh]

I have a bunch and have come up pretty empty. There are a billion things about rain barrel diverters and overflow setups to link multiple barrels, but nothing to stop the flow of water into a barrel. I was able to find some bungs with a 3/4" knockout port so I'm thinking maybe i can find a float valve that's tiny enough to fit down in thru the bung, and work vertically and with a RO water line adapter. I was hoping someone's stuck a float valve in like that, or there would be some simple drop down in pipe that treads with a float and makes it easy. There are some that look kinda close, but they still have a hose output and are meant to go in the side of a massive tank instead.

 

[TorturedSoul]

Toilet fill valve, lol. The supply line for one would easily fit through a 3/4" port with room to spare, so you wouldn't need to have the top off the barrel any longer than it took you to install it and adjust the float rod (if applicable) to suit. You could leave the rest of the port unblocked, for air equalization, or get fancy and run a vent line, then caulk the opening shut.