THC metabolites are expelled via the matabolizing of the fat in which they are stored, in the large intestine, where water is also finally absorbed into the body, thus it's appearance in urine.
Since THC is stored in fat cells, excersizing can cause those fat cells to release their load, and it is possible for one's THC level to rise after excersizing even if no smoking is occuring. That happened to me. It was awesome :rolleyes; to show detectable levels 60+ days after cessation of intake, just based on legacy use and a "Boot Camp" type excersize program I was doing at the time. It finally did taper off, but it was there, even on the cheap drugstore type, instant read test.
If you do excersize, make sure you do the fiber thing regularly. Trust me on this one.
My doc said that loading up on fat heavy foods will also serve to "bury" the older THCfat and reduce that subsequent THCfat level in the LI and by extension, the urine, BUT only temporarily so if you have some advance warning, that may cloak that use.
In order to reduce the amount of THCfat present in the LI, one can increase one's fiber intake in order to more throughly vacate that area. Increased water intake helps in flushing the bodysystem in total.
As stated previously, creatine levels are checked to avoid simple water loading and visual inspection of color is also considered in rejecting a sample.
Increasing ones intake of multi-vitamin ( B ) will help to adjust color away from the clear which is a cue to the test giver that water loading may be occuring. You could also eat foods that help that aspect.
NOTE- A properly hydrated body will not be showing a lot of yellow in the urine stream. Heavy color can indicate a dehydrated or more seriopus medical condition or other metabolites from other foods / drinks (aspargus / coffee for example)
The first pee of the day is the one you do not want to have tested. You want to have voided yourself fully before any testing.
Learn what is "normal" for your body and do not let some non-medically trained, hourly employee try to hold some arbitrary standard as "normal" over your head. Learn the procedures for the testing procedure and adjust your behavior accordingly. Defend your clear pee!
Good luck with that.
BTW...to the larger discussion....
Pre-employment drug testing is bullshit for most occupations. Truck/Bus/Commercial Drivers, Heavy Equipment / Train Operators, Law Enforcement, there are exceptions, I'll grant you.
Give me a shop full of pot heads over ones drunk, or a bunch of "week end" coke-sters, anyday.
Tweakers still suck, though, no matter how much or for what reason.
Meth is a Terrorist Weapon System.