This is the best way to pass a drug test:
Do a 3-4 day modified fast (1000-2000 cals/d), very low carb and high protein. This gets recent fat stores mobilized to rid the body of current lipophilic drugs (THC, steroid esters, etc..) followed by a serious 48hrs carb load leading up to test. The carb up ensures you are burning glucose and storing fat at the time of the test and not excreting it, so a calorie surplus is required. Also, you do not want to drink too many fluids if you didn't fast because this can actually concentrate lipophilics in the urine, not dilute them! Diuretics can only dilute water soluble drugs or lipophilics that can form water soluble salt (stims like amphetamine or ephedrine). If you have used a a stim recently, you can acidify your urine with ammonium chloride, aspirin or vitamin C for a day or two kinda like the lipophilic protocol, then make sure your urine is basic when you take the test. A teaspoon of baking soda is a cheap way to do this and works well. This makes the stim clear out fast by forced acid diuresis before the test and hold on to any stims still left in your system during the test period so they are temporarily not excreted, just in case some were still in your system. Otherwise high water intake is good if you fasted properly and don't forget to take creatine. The monohydrate works at about 1g/50lbs of body weight. More than that will show an abnormal result and automatically get further testing or dismissed completely as a positive sample, but if your urine is too diluted, it will fail for low creatinine values and test bad too, so you need a little creatine for sure. Plus, take a B-complex to make sure your urine looks yellow. This will make it look concentrated and dilution will not be suspected, even if electrolyte values are low. If the urine is too light, it will fail visual inspection automatically before it can even be tested.
I've passed dozens of urine tests over the years, even doing stuff to the very night before in several cases (that was stupid though and I don't recommend it) plus I worked in a lab for about 2.5 years were I could test myself constantly so I gathered a good bit of data from personal experiments. However, if you're on Deca or Laurabolin, you better say your prayers too, because the metabolites are detectable at very low levels and can persist for over a year. In that case, the fast is the best shot you have, or a masking agent. Orals usually clear fast though (a week or two).