More likely, the water consumption is what allowed you to test negative. More likely than the exercise and sweating. By consuming fluids, youve effectively diluted the THCA concentration in your bladder to where the urine sample registered below the cutoff thresholds of the drug screen.
Exercise during the 3 days prior to a U/A can work against you. Thats because when fat cells burn, the stored THCA are released back into the bloodstream and end up in the urine to be detected. For this reason, exercise should be avoided for those 3 days to avoid releasing a bunch of THCA into the bloodstream, which will end up in the urine.

Contrary to popular belief, sweating is hardly of any help because very little THCA is excreted via sweat. You can sweat enough to fill many 5 gallon buckets, yet the amount of THCA being excreted would still be miniscule. The rest of them are being excreted via the urine and bowels.