PDX, to give you an idea (because I was wondering the same thing about the proverbial faint line), I decided to test my Quick Fix with my home test kit today. While the line was definitely darker than the test I took at the same time with my own urine, the QF line was still noticably fainter than the control line. I've read a few posts where people have tested tap water, and the THC line was still faint. It may depend on the type of test, but who knows. Hope this helps.