Even though the court wishes for you to have 0 ngs in your system, there is no zero-tolerance test because all drug testing devices have cutoff levels (including the GC/MS which quantifies) and if you test below the cutoff level, its a negative regardless.

Drinking water days or weeks before the test is useless. THC is not water soluble, therefore you cannot permanently flush THC from your system. It may cause frequent urination, but it has no effect on the rate in which the kidneys filtering the THCA from the bloodstream. Even while youre drinking water, you'll still be burning fat cells, releasing the THCA into your bloodstream, which will be picked up by the kidneys and end up in your bladder to be detected.
Drinking fluids is only helpful on the day of the test because youre diluting (thinning out) the THCA concentration thats present in the bladder. This action is only temporary - once all the water consumed had been voided out, the "dirty" donor will resume testing positive for THC.
Exercise is only helpful if you have weeks to prepare for the drug test. 3-5 days before your test, you need to avoid all fat-burning activities and be as lazy as possible so you dont release a bunch of THCA into the bloodstream, which will all end up in your urine to be detected.