most helpful answer well i'm no expert on this but i doubt you messed up the drug screen. first of all 500ml is not very much water for the kidneys to process especially not over the course of four hours. second many people who take multivitamins are subjected to random drug screens. there's no evidence taking a vitamin affects the results in any way. urine drug screening tests are quite sensitive. they will detect very small concentrations of molecules. if it were possible to skew urine drug screens simply by drinking excessive amounts of water everyone who takes illicit drugs would beat the tests by doing just that. but you don't hear of that happening. by the way i would never advise anyone to try drinking excessive amounts of water in order to "cheat" a urine drug screen. drinking large quantities of water over a short period of time can be very dangerous leading to a potentially fatal condition called "water intoxication. " wishing you well!
how much water does it take to dilute urine. i am worried i might have accidentally diluted a urine sample. i consumed a a 500ml bottle of water 4 hours before the test and my urine was a bright yellow when i finally took the test. it did not appear a dark yellow but it was a lighter yellow. i also took a multivitamin that morning (same time as the bottle of water) could that mess up a urine drug test?