What is going on
Hair does not dissolve. It snags on the drain crossbars and the curve of the trap, and soap film coats it until it forms a mat that lets water through slowly and then barely at all.
Hard water adds mineral scale that narrows the pipe and gives the buildup more to cling to.
What you can safely try
- Remove the drain cover and pull out what you can reach with gloved fingers or a plastic drain tool
- Flush with very hot tap water afterward
- Fit a hair catcher over the drain to keep it from coming back
What to avoid
Chemical drain openers sit in the trap when they do not clear the clog, and they can damage older pipes and finishes. They also make the job hazardous for anyone who has to open the drain afterward.
When professional help makes sense
If the drain is still slow after the cover and trap area are cleared, or if the tub or a nearby toilet is also slow, the clog is further down the line and needs a drain machine.