Problem
The bathroom sink does not drain properly and water backs up in the basin.
Possible Causes
Hair clog
Soap scum buildup
Blocked P-trap
Deeper drain blockage
How To Fix It
Remove the drain stopper
Pull out visible hair or debris
Run hot water to test drainage
Clean the P-trap if accessible
When To Call A Professional
If the sink still does not drain after removing buildup, a plumber may need to clear the drain line.