The 6 Most Common Causes of Bathroom Sink Clogs
A clogged bathroom sink is one of the most frequent plumbing calls we get. Understanding what causes these clogs can help you prevent them — and know when to call for professional help.
1. Hair Build-Up
Hair is the #1 cause of bathroom sink clogs. When you shave, wash your face, or brush your hair over the sink, loose strands go down the drain and accumulate over time.
Long hair is especially problematic — it tangles around other debris in the drain, forming a solid mass that's difficult to remove.
Prevention:
- Install a drain screen or hair catcher ($3-$8 at any hardware store)
- Remove visible hair from the drain opening weekly
- Pull out any accumulated hair from the stopper mechanism monthly
Fix:
- Try a drain snake to pull out the hair ball
- Use the baking soda and vinegar method to dissolve organic buildup around the hair
- A bent wire hanger with a small hook works in a pinch
2. Soap Scum Accumulation
Every time you wash your hands, soap residue goes down the drain. Over time, this sticky mixture of soap particles, dirt, and minerals from hard water coats the inside of your pipes.
Chicago's hard water (8-10 grains per gallon) makes this problem worse — mineral deposits combine with soap to create a stubborn, chalky buildup.
Prevention:
- Wipe down the sink and drain area after use
- Switch to liquid soap (produces less scum than bar soap)
- Do a monthly hot water flush
Fix:
- Pour boiling water down the drain to dissolve soap buildup
- Use baking soda and vinegar to break down the deposits
- For severe buildup, a professional drain cleaning is the most effective solution
3. Toothpaste Residue
Toothpaste seems harmless, but the thick paste coats pipe walls and acts as a glue for hair, skin cells, and other debris. Over time, this creates a layered buildup that restricts water flow.
Prevention:
- Rinse the sink thoroughly after brushing
- Run warm water for 10-15 seconds to flush residue
4. Foreign Objects
Small items accidentally fall into the sink more often than you'd think:
- Toothpaste caps
- Earrings and jewelry
- Bobby pins and hair clips
- Contact lens cases
- Small toy parts (if you have kids)
These objects lodge in the P-trap (the curved pipe under the sink) and create instant blockages.
Prevention:
- Keep small items away from the sink edge
- Use a drain cover
- Close the stopper when not actively using the sink
Fix:
- Place a bucket under the P-trap, unscrew it, and retrieve the item
- If you're not comfortable with this, call a plumber — they can retrieve it quickly
5. Grease and Oil Buildup
While more common in kitchen sinks, bathroom sinks also accumulate oily residue from:
- Face wash and makeup remover
- Hair products (gels, oils, serums)
- Lotions and moisturizers
- Shaving cream
These products coat pipe walls and attract other debris, gradually restricting flow.
Prevention:
- Wipe excess product off with a paper towel before rinsing
- Run hot water after using oily products
- Monthly baking soda and vinegar treatment
6. Old Pipes and Plumbing Issues
In older Chicago homes (especially those built before 1960), the plumbing itself can be the problem:
- Corroded pipes have rough interior surfaces that catch debris easily
- Galvanized steel pipes develop internal rust and scale that narrows the pipe diameter
- Misaligned joints from settling can create catch points
- Tree root intrusion in underground drain lines (less common for bathroom sinks but possible if the branch line connects to the main sewer)
Fix: If your bathroom sink clogs frequently despite cleaning, the pipes themselves may need inspection. A sewer camera inspection can reveal the exact condition of your drain pipes without any digging.
When to Call a Professional
Try DIY methods first for minor clogs. Call a plumber when:
- The clog keeps returning within days or weeks
- Multiple fixtures are draining slowly
- You hear gurgling from other drains
- Water backs up in the tub when you drain the sink
- The sink has been slow for a long time and is getting worse
Bathroom sink won't drain? Call Plumbers 911 Chicago at 833-758-6911 for professional drain cleaning throughout Chicago and the surrounding suburbs.