Contrary to popular belief, line intensity is not proportionate to THCA levels in the urine. If it were, then completely drug-free specimens like synthetic urine controls (as well as your tap water tests) wouldnt be producing faint lines on an assay.

A faint line is still a negative. A negative is a negative.
Burnt Toast Reviewed by Burnt Toast on . Different test different results I have used several brands of THC strip tests. On one recent batch the second line is very faint even when testing a known negative and even tap water while another brand test used at the same time has a nice bold line. The test with the very faint line seems to be very sensitive to even the slightest amount of THC. After getting repeated negative results, then taking as little as one or tow puffs - the line becomes almost invisible. At the same time the other brand shows a clear second line. Rating: 5