A slow drain is almost always a partial clog: hair and soap in bathroom drains, or grease and food in kitchen sinks. If only one fixture is slow, the blockage is in that drain. If several drains are slow or gurgling, the problem is probably in the main sewer line and needs a plumber.
Reviewed by Ron Olsen, Master Plumber, certified in Washington
Why Drains Slow Down
- Hair and soap scum
- The most common cause in bathroom sinks, tubs and showers. Hair binds with soap residue just below the stopper.
- Grease and food waste
- Fats cool and harden inside kitchen drain lines and trap food particles.
- Mineral buildup
- Hard water leaves scale that narrows pipes over time.
- Blocked vent
- Plumbing vents let air into the system. A blocked vent slows drainage and causes gurgling.
- Main line clog or roots
- If several drains are slow, the blockage is likely in the main sewer line, often from tree roots or buildup.
What You Can Safely Check
- Remove and clean the stopper or strainer.
- Use a plunger with a good seal, covering the overflow hole on tubs and bathroom sinks.
- Try a hand drain snake on hair clogs in tubs and showers.
- Flush kitchen drains with hot tap water to move grease. Avoid boiling water on PVC pipes.
When to Call a Plumber
Call a plumber if more than one drain is slow, if a drain gurgles or smells, if water backs up into another fixture, or if the clog comes back within a few weeks.
The repair is usually part of drain cleaning, which explains what the plumber does and what affects the cost.
Drain Clogs by City
What our city pages say about drain clogs:
- Florin, CA: Kitchen and main lines clog with grease and roots.
- Auburn, AL: Shared student houses clog kitchen and tub drains fast.
- Mission, TX: Kitchen lines and main drains clog with grease and roots.
- Horizon West, FL: Grease and wipes block kitchen lines and the main to the street.
- Sunrise Manor, NV: Older kitchen and laundry drains narrow with grease and scale.
- Severn, MD: Kitchen and main lines clog with grease and wipes.
- Kansas City, MO: Many homes have basements, so sewer backups and sump pump failures are common after heavy rain.
- Ames, IA: Grease, hair and wipes block lines in busy houses and apartments.
Other Drain Cleaning Problems
Slow Drain Questions
Are chemical drain cleaners safe?
They can damage older pipes, harm septic systems and cause burns. Mechanical methods are safer and usually work better.
Why does my sink gurgle?
Gurgling means air is being pulled through the trap, usually because of a partial clog further down the line or a blocked plumbing vent.