How to prove evap vs. positive

Kira • 15 mo. 👶🏽🎀
Hi ladies!
So I read that a way to tell an evap line from a faint positive line is to drop water into the testing area, where the urine goes. If it's an evap it'll disappear, if it's positive it will stay. Has anyone tried this and turned out to be pregnant? Or tried it and wasn't. This "technique" is used when the test has dried/ or past the time frame btw.