I really don't think it will.. the aspirin is not going to hide anything.. and all the water will do is dilute the sample..a dilute sample is a failed test most of the time.. I have even failed after using carbo drinks..I used to buy clean urine for passing test but Arkansas has banned this stuff.. http://bmj.bmjjournals.com/cgi/conte...326/7384/300/a

BUT if they are not sending it to a lab I would dilute the hell out of it. Don't use a time line just drink lots and lots of water..