Weed can stay in your system for up to 30 days, I think the rule of thumb is 1 joint, 1 month. There is only one way to get it out faster and that is to exercise. THC is a fat solube, working out and exercising burns away fat and the THC metabolites inside fatty tissues. THC is not a water solube so drinking water will only mask your test just like all the detox drinks, pills, etc. My source of info http://my.marijuana.com/4-6b.php3 and http://my.marijuana.com/7-11b.php3