I havent heard it done that way, but just got back from a drug test and I passed. I woke up this morning and smoked. Then at about 2 I drank ONE packet of Certo mixed into a glass of water. It tastes really sweet but has NO flavor so this was not a plesant experiance. After that I drank about a half a gallon of water and peed 3 times between drinking the Certo and taking my test. I passed and I got the job. I know for sure that if I had just drank the water that this would have a different ending, I dont know why Certo works. But it seems to. But dont drink 2 packets of it, its rough enough on your stomach!