thanks for getting back to me. not quite sure what you mean by void. i just started drinking water at a pretty good pace a few days before the test. the test was 8 days after my last smoke (i smoke 2-3 x month). bought 4 home tests cuz i'm freaking out. passed all of them, the last one the morning of the test, about an hour and a half before. went an took the test after drinking some more water. i guess i'm more worried about how accurate the at home test. picked it up at walgreens. any feedback is good. from what i hear the home test is pretty reliable. wasnt sure if anyone had any experience.