This is what u do. Vinegar will only will only raise the ph of your urine. Don't drink large amounts of water days before the test because your causing yourself unbenificial discomfort. Water does not get THC out your system faster because it is only fat soludable. Water only dilutes the THC in your system. It's like putting a lot of water in kool-aid, only that your putting a lot of water in your body so that the machine can't detect it. So just drink about 8 glasses of water first thing in the morning. Piss a few times before taking the test because this urine is dirty and contains alot of drug metabolites. When u piss in the container don't give the beginning or end of the stream, give a mid-stream sample, make sure it's enough though. And right you should start eating big so that u put your body in a fat storing stage. This will keep all the THC metabolites in your lipid tissue (fat) and out of your urine. The THC caculater program dosen't work. It is inaccurate. But since your a infrequent user u should pass