What steps should I take to troubleshoot a tub drain that makes noises?

Answer by  jody1723 (65)

A blocked or inadequate vent. Check to see of you have an "s" shaped trap. If you do, it's probably not vented well and you should update your pipes.

Answer by  ServicePlumber (211)

It's ordinary that tubs will make a 'glug' noise when draining, and seem to be draining slow. This is caused by the fact that tubs use 1" 1/2 drain lines to move a very large amount of water. This problem is made worse when air inlet pipes are far away.