What marijuana detox works best?

I smoked today and I may have to take a pre employment drug test for a job I really need. I know that I shouldnt be smoking pot, and if it didnt help me sleep so well I wouldn't do it at all. I just found out about the job today, after I had already smoked, so my question is what is the best way to pass a drug test by tomorrow? I already only drink water, and my current job has a lot of physical labor to it so I do sweat a lot. So is my best bet to continue to drink a lot of water and just hope for the best or should I buy a detox kit? Which would be more effective on such short notice?