The most common cause for a faint T-line is that there is drug present in the sample but not enough to trigger a positive result. There Is Remaining Drug in the Urine. Math Word Walls Scaffoldedmath Com Pinterest These urine tests are passfail. . I took about 5 at home tests and they all had a faint line which indicates a negative tests. About a week later I got a call from the drug testing place telling me that they detected marijuana in my sample and had to report it to my employer. The THC15 and THC20 ütest devices represent the highest sensitivity for antibody-based THC drug screens meaning a faint T-line would still indicate that the drug concentration is too low for a laboratory to call positive. If a line shows up your test is negative meaning you passed. Literally just drink one packet mixed in with a yellow bottle of Gatorade about 2 hrs before test try to. We can help investigators analysis negotiation etc. ...