If you know you're required to take a piss test for work, the best advice of all is to avoid them completely. If the test is planned ahead of time, then simple self-control will help you pass the drug test. Anyone who knows they have to take a drug test but still chooses to use drugs probably deserves to fail in the first place.
2. Eat a Lot of Fiber
There’s more to flushing out toxins than just urinating. Shitting helps get rid of toxins, and fiber is your best friend when it comes to number two. Fruits, veggies, beans, sawdust - whatever it takes to get you to drop some friends off at the pool.
3. Water! Water! Water!
Water is the obvious one, but green tea is also another great one. Green tea, and other drinks that contain caffeine can act as diuretics which make you urinate more often, which is crucial if you are wanting to pass a drug test. Drinking too much water will definitely flush out the majority of the toxins, but it also makes it somewhat obvious that the samples are being diluted intentionally.
4. Up Your Creatine
Another problem with drinking a lot of water is that the creatine levels may get diluted. If the testers get suspicious that the sample has been intentionally diluted or tampered with, they may test for more than just the substances originally tested for. Creatine is usually one of those, and it definitely becomes lower as you drink more liquids. Taking creatine supplements along with B vitamins will keep your sample as normal as possible while still being almost substance-free
5. Add Some Color to Your Pee
To avoid the suspiciously clear, almost water-like urine that comes with drinking a ton of water, take some B vitamins prior to the test. Taking these supplements will keep your pee yellow despite the influx of water coming in. This is crucial if you don't want to arouse any suspicion.
6. Drain It One Last Time
This one seems obvious, but it should also be done properly and at the right time. Your first few pees of the day, and especially after doing drugs will always contain the most toxins and substances that are being tested for. Also try to empty the tank right before your drug test, allowing you to buy some more time and drink some more water before a sample is taken.