I think morphine and most opiates clear your system in 48-72 hours, even the metabolites, except methadone of course ,it stays in your system for a lot longer as you know. As for testing positive for opaites, I have had to take piss tests in the past for doctors when I was having chronic pain and even though I would be high as hell,and take a number of opiates the night before and that day, 1/2 the time, my system showed no opiates, which was crazy,becasue I always had them in my system then, and becasue of the drug tests the doctors thought I was selling my pills sometimes!! Plus about 1/4 of the time I would test positive for PCP, which I had not done for years then, and which only stays in your system 5 to 7 days tops anyway, but that shows how shitty the urine tests can be! Showing no opiates in my system when they were there in mass and showing that there was PCP ,when I had not smoked any for 4 or 5 years!! lol..fucked up drug tests