Troubleshooting: Try this First
Attack the clog in the following order:
Step 1. Fill the sink with water and vigorously pump up and down with a plunger. Direct pressure at the clog by stuffing a wet rag into the overflow hole, says Joseph Wood, owner of Boston Standard Plumbing & Heating, in Massachusetts.
Step 2. Pop out the drain stopper (3)—hair and soap scum tend to ball up at its base—by unscrewing the nut (1) at the back of the drain pipe and retracting the pivot rod (2). Extract the blob with a wire clothes hanger (4).
Still no luck?
Step 3. Remove the P-trap with tongue-and-groove pliers, twisting in the direction of the lower jaws. Have a bowl ready to capture the deluge. Inspect the trap. If the blockage isn’t there, remove the trap arm and feed a pipe snake into the stub-out to release the clog.
Originally featured in 25 DIY Fundamentals, where you can find loads of other skillbuilders.