Originally Posted by jaycount
A long time. You can use ph strips or a ph meter to determine when it's reached the end of it's life but I read alot about folks filling a bucket with starsan soln, sealing it, and using it time after time... A sealed keg would be even better.
I keep a carboy loaded with Star-San solution and use it repeatedly, dumping it into my sanitation bucket for brew days, racking days, kegging days, etc. I test it each time to make sure it's still hanging in around pH = ~3 and as long as it's still viable I reload the carboy and cork it until the next use...