Advice on detoxing?

I have a drug test coming up for a new company I just got hired onto. Now I wasn't expecting a drug test and they just informed me I need to complete one before my postion is finalized. Sept 5 is my starting date, though they will be getting the test results before then and give me the green light or not if I failed. So I have, starting today, until approximately august 31, 14 days to detox. What is the best way to go about this? Drink tons of water and cranberry juice. There is a pill i can get at one of my local stores that detox you within a day or 48 hours, not sure how safe or effective it actually is. Is all I can really do to detox is drown my life in juice and water until the test date?

Thanks for any advice and to all future replies. Much appreciated!