I think is it is possible to pass. Depending on your level of thc in your body. I have always just used the ech/goleden seal, so I feel comfortable with it. With the water you are diluting the thc in your body. So there is still some in your pee when you do the test, it is just not enough to go over the allowable limit.
Remember, as a latch ditch effort if you have nothing else. Get some soap scum under your fingernails and run your pee over it when your testing. It will most probably either give a negative or a false reading which will mean a retest at a later date. More time to get prepared. Late