Trap leaks under the sink: the dry-paper test

Most under-sink leaks are invisible on a quick look because the trap is dry at the moment you open the cabinet — the leak only shows while water is running or just after. The dry-paper test takes thirty seconds: wipe the trap and fittings completely dry, run the water and fill-and-drain the sink, then press a dry paper towel around each joint. Any damp spot names the joint that is leaking. It also catches the slow weep that has been quietly swelling the cabinet floor for months — damage an inspector reads as a plumbing deficiency and a moisture story. Put the paper in the turn kit next to the flashlight. What is your fastest leak test? — Otto Mergl, Admin