i think it depends on the tests..... my drug tests get sent into a company which means it has to be at least a couple days b4 they get tested.... i'm sure it depends on the test and what it tests for... the only thing that i could see being a concern is the creatnine levels, if the test doenst test for this i have no idea how it could determine if the piss was old, or even if the piss isnt just apple juice, but most hometests dont test for creatinine. I'm not even sure if the creatinine levels decrease over time, but i think that i've read that they do. But anyway if someone has anything to ad to this i'd be interested to know to, cause i'm in a similar situation where this info would come in handy.