Plumbing Questions? Ask a Plumbing Expert.
Hello my name is***** am a plumbing contractor and taught plumbing theory at UNM for 5 years. The first thing to check for after the drain plug is for hair in the P-trap. This can sometimes be done by putting a metal coat hanger with a hook Bent into the end down the over flow hole after removing the over flow plate and linkage. Try pushing the hanger in as far as possible then pushing and pulling on the hanger to catch up the hair then pull it out slowly. If this doesn't work you may want to purchase a small hand operated sewer snake.
One thing to think about is if all of the rest of the house are draining well or if any other fixtures are running slow, this could indicate a larger back up.
If you need anything else let me know?