Honestly.. You shouldn't. It doesnt work, i am not sure what you are trying to rid your system of, most drugs stay in urine 3-5 days max, execption being marijuana, which is typically 14-30 days, benzos 3-30 days depending on type and frequency, methadone up to 3 weeks even if used infrequent. My advice drink at least 1 gallon of water each day until the test and at least a gallon 3 hours before test urinate at least 4 times before submitting. Take B vitamins to prevent urine from being clear. If this test will be sent to a labcorp facillity then i dont know for certain that will work, otherwise you will be fine. The idea is to water down the concentrated metabalytes of the drug which is what tests read, you want to reach a low enough concentration that it will not be high enough to create a positive result.. Flushing does not work, only time will do that, dilution is the goal, and water is the only method that has ever worked in my experience. Good luck