methadone piss testing for drugs,and how can u pass?

so i know somebody who had to go to the clinic and get his methadone drink and carry for the day, however he had done some opiates the day before and as u know that is against the rules...so they were closeing and trying to make him piss and hurry up, he said he cant and she said if u dont u cant get ur methadone, so in a panic he went to the washroom mixed some of my methadone in the pee bottle with some water, do you think that they will be able to tell!? or will he pass with no drugs and just methadone in the pee?! he might end up getting kicked off this if they detect what he has done, so i am kinda freaking out and not sure what to think. i want to believe it will work , if anybody knows any info!! :-| please get bak to me ASAP :-( thanx guuys!!