Quick answer
A drain that keeps clogging usually has buildup farther down the line than a plunger or strainer can reach: hair, grease, soap residue, wipes, or tree roots in the sewer pipe. Clearing one fixture is a quick fix. If several drains are slow, or the clog returns within weeks, the blockage is likely deeper and needs a cable or camera inspection.
Why clogs come back
Most repeat clogs come from partial clearing. A plunger or a quick pass with a tool can punch a hole through the blockage so water flows again, while the material coating the pipe walls stays in place. New debris then catches on it and the opening narrows again.
The second common reason is a steady supply of the same material. If hair, grease or wipes keep going down, the clog will keep returning no matter how often it is cleared.
Common causes by fixture
Where the drain is tells you a lot about what is probably in it.
- Bathroom sink and shower: hair mixed with soap scum. Hair is one of the materials utilities list as a cause of blocked pipes.
- Kitchen sink: fats, oils and grease, plus food scraps. These build up in pipes over time. Cooled grease sticks to pipe walls and catches other debris.
- Garbage disposal drain: the same grease and food buildup, often worse because ground food settles in the pipe past the disposal.
- Toilet: too much toilet paper, or items that should never be flushed. The City of Bellevue says sewer systems are meant only for water, human waste and toilet paper, and lists wipes (including those labeled flushable), paper towels, sanitary products, dental floss and diapers as items that block pipes.
- Laundry standpipe: lint and fabric fibers.
One fixture or the whole house?
This is the most useful question to answer first. A clog in one fixture is usually in that fixture's trap or branch line. If multiple fixtures are affected, the problem is likely in the main sewer line.
Signs of a main line problem include several slow drains at once, toilets gurgling when other fixtures run, water backing up in a tub or shower, sewage odors, and standing water near floor drains. Lower drains such as a basement floor drain or a ground-level tub often show backups first.
Tree and shrub roots are a known cause of main line blockages. The City of Bellevue notes that roots can grow into sewer pipes, often through the top of the pipe, and eventually cause a blockage. It also says so-called root killer products rarely work, because the chemical settles at the bottom of the pipe while the roots enter from the top. Pipes can be split by roots, which can eventually lead to collapse.
Safe things to try yourself
Start with the simple, low-risk steps. Stop if you meet resistance or the water level rises toward the rim.
- Remove standing water if you can, so you can see what you are working on.
- Clean the stopper or strainer. In bathroom sinks and tubs, pull out the stopper and remove the hair and gunk attached to it. Wear gloves.
- Use a plunger sized for the fixture. Cover the opening completely, with enough water to submerge the cup, and plunge firmly for 20 to 30 seconds. For a sink with an overflow hole, block the overflow with a wet rag so pressure goes into the clog.
- Try a small hand drain tool (a plastic barbed strip or a small auger) in a bathroom sink or tub to pull out hair. Do not force it.
- Flush with plenty of hot tap water afterward. Do not use boiling water on a toilet bowl or in plastic pipes.
Prevent repeat clogs
Prevention is mostly about stopping the supply of clog material.
- Put a fine strainer over the shower and tub drains and empty it after use.
- Wipe greasy pans with a paper towel and put it in the trash. Do not pour fats, oils or grease down the sink. InSinkErator, a disposal manufacturer, says never to put any type of fat, oil or grease in a disposal or down a sink drain.
- Flush only toilet paper and human waste. Put wipes in the trash, even if the package says flushable.
- Feed coffee grounds and eggshells into a disposal gradually, or put them in the compost or trash, because they settle like sediment in the pipes.
- If roots have caused a problem before, schedule inspections rather than waiting for the next backup.
Why chemical drain cleaners are a poor idea
Liquid drain openers can contain lye (sodium hydroxide), potassium hydroxide, sulfuric acid or hydrochloric acid, according to MedlinePlus. These can cause burns to the skin, eyes, mouth and throat, and breathing problems from fumes. Poison Control describes drain cleaners as caustic, with damage that is immediate and cannot be reversed, only treated.
There are also plumbing reasons to avoid them. A chemical that does not clear the clog leaves a pipe full of standing caustic water, which is a hazard to anyone who then opens the trap or uses a tool. Sewer-line guidance from HomeTips notes that chemical cleaners are usually ineffective on main line clogs and can damage pipes.
Never mix drain cleaners with each other or with bleach, ammonia or other cleaners. The New Jersey Department of Health warns that bleach combined with drain cleaners can release chlorine gas or other fumes, and that different brands of drain cleaner can react dangerously.
If someone is exposed, flush skin or eyes with water and call Poison Help at 1-800-222-1222. Call 911 for a life-threatening emergency.
What professional drain cleaning involves
Drain cleaning generally means running a motorized cable (auger) through the line to break up or pull out the blockage. For heavier buildup, a plumber may use a tool that scours the pipe walls more thoroughly than a basic cable.
A camera inspection feeds a small waterproof camera through the pipe, so the plumber can see what the blockage is and where it sits. It can show grease coating, a section of damaged or offset pipe, or roots entering at a joint. That information matters when a clog keeps coming back, because it separates a cleanable buildup from a pipe that needs repair.
We do drain cleaning and sewer line repair, so a camera look at a recurring problem is often the point where a repeat clog stops being a mystery.
When to call Pyper
Call a plumber if more than one fixture is slow or backing up, if sewage is coming up in a tub, shower or floor drain, if a clog returns within weeks of clearing it, or if a plunger and hand tools make no difference.
Pyper Plumbing handles drain cleaning, sewer line repair and emergency plumbing in Snohomish, Skagit, Whatcom and Island counties. If you are not sure whether you have a fixture clog or a main line problem, describe what you are seeing and we can help sort it out. We do not do septic work, so if your home is on a septic system, that part of the problem will need a septic specialist.
Common questions
Why does my drain keep clogging after I clear it?
Usually the clog was only partly removed, or the same material keeps going down the drain. Hair, grease, soap residue and wipes build up on pipe walls. If several drains are affected, the cause may be a deeper blockage or roots in the main sewer line.
Is it safe to use Drano or other chemical drain cleaners?
We recommend against them. Many contain lye or strong acids that can burn skin and eyes, and they can react dangerously if mixed with other cleaners. They are also often ineffective on deep clogs. Use a plunger or hand tool, or call a plumber.
How do I know if it is a main sewer line clog?
Several drains are slow at once, toilets gurgle when other fixtures run, water backs up in a tub or shower, or you smell sewage. Lower drains such as basement floor drains often show the problem first.
What does a camera inspection show?
A small camera is fed into the pipe so the plumber can see the blockage and the pipe condition, including grease buildup, roots, or damaged sections. It helps decide between cleaning and repair.
Sources
Facts in this guide come from the following references. Local rules and manufacturer instructions can differ, so follow your utility and your equipment manual.
- City of Bellevue: Preventing Sewer Backups
- HomeTips: Sewer Line Clog Signs
- MedlinePlus: Drain Opener Poisoning
- Poison Control: Caution with Caustics
- NJ Department of Health: Hazard Alert, Mixing Cleaners
- InSinkErator: What Not to Put in a Garbage Disposal
This guide is general information, not a substitute for an on-site inspection. If you smell natural gas, leave the building and call 911 or your gas utility. Pyper does not perform gas line work.
