i used a squirt bottle of water to test joints for a small leak that was causing a few bubbles in the pump basket. found it at a coupling on the main drain line coming out of the ground. repeated attempts to fix it failed. until it dawned on me that maybe it wasnt at the TOP of the coupling but the BOTTOM that was just beneath ground level. so i dug out around the pipe to expose it and sure enough, that is where the leak was. fixed it using primer then heavy dose of glue. the water i was squirting around the top of the coupling to test for leaks was draining to the bottom of the fitting that i couldn't see. duh.