Well THC is stored in your fat cells, thus making it take up to a month to get it out of your system. Drinking water MAY help IF you have recently smoked, (first time/first time smoking within a few months) but no, even if you drink 5 gallons of water a day it still would not be out of your system.
@Sir Bongs- Your best bet would be to buy synthetic urine from a local head shop, or just order it. I'm not sure what it is made from, but there are multiple cases of it being an effective product for passing piss tests. I wish you luck dude.