The problem with drinking a lot of water, is that MAYBE they'll do a "Dilution Test"... which is to see if your urine is, um, "diluted". If they find it IS diluted, they'll answer the test as "Inconclusive", and ask you to re-test at a later date.

You CAN get away with it, because there are labs/people/tests that DON'T test for dilution, so your piss will have the THC level below the acceptable treshold, and they won't care if it's diluted or not... so, hope for the best on that one.

The problem with VINEGAR::: Vinegar "masks" the THC in your piss by changing the pH level... so, you can imagine... they test for pH. If it's found outside the acceptable range, you'll be re-testing at a later date. Again, it's about luck: the lab you go may NOT test for pH... but that's just a lucky shot.

BTW: I prefer to be positive than to drink.. ughhh... vinegar...