Once every two weeks. One hit 2 weeks ago, average height and weight. Now are you fat (not weight, but more fat to muscle mass) or are you lean muscle mass? Do you get plenty of sleep? how often do your urinate? how long have you been smoking once every 2 weeks? Liver, kidneys, lymphatic system working at 100%? ....Forget it - There are many variables to the question to get a solid single answer for you. On AVERAGE - which is to say that if we took a group of people some would be higher, some would be lower - dividing the results by the number of people we get an AVERAGE. On Average its 14 to 21 days for occasional or 'low' pot use. For constant use (daily, more than twice a week) that can extend to 30 to 45 days. There are variables, such as how well your body actually functions in cleaning. THC (the active chemical in pot) is not water soluble, it can get deep into the fat tissue and remain there as long as the fat is there. Contrary to popular belief fat does not remain forever, your body slowly circulates the old for new - As with all tissues. So in about 3-4 years your last hit of pot will finally leave your body as the trade off on fat tissue takes place. In instances where a person has smoked heavily for years and then cuts back to weekly or so - their level of THC in the fatty tissues is higher and remains high since they continue dosing. It is possible for a person who hasn't smoked for up to 6 months to have a sudden increase in the THC to levels high enough to detect in urine test - this is usually after a sudden increase of exercise or the start of a diet - what has happened is that they are burning fat - the fat released the THC as it is burned. Other chemicals do this as well, THC is not really that remarkable in its tendency to stick around. The Answer is actually not an easy one. An NO you can not flush the system - you can't flush out any drug faster than your body works. The Liver, kidneys work at their rate no matter if you dehydrate it (do not drink) or if you hyper-hydrate (drink lots of water) or if you use a diuretic (something that makes you pee a lot). The drug has to get down to lower levels in the fatty tissues and that is a chemical process not a mechanical one - meaning it has to due its thing in its own time.