I have never been drug tested but alcohol shouldn't stay in your system for more than 24 hours. However if you are still unsure and want to play it safe you could always drink a lot of water. It does work. The water flushes out your system. You can do this by drinking 1 gallon of water 1 hour before test. Start 1 hour before the test and drink it all up. It works because by the time you take the test you will only be pissing out water. Just don't drink too much because you can kill yourself or too little because it won't fully flush out your system. Though it is not fun or easy to do.