How to Unclog a Sewer Backup

Household sewer blockages can be created through the buildup of cooking fat or oil sticking to the inner walls of the pipe, excess toilet tissue flushed into the sewer line, or even tree roots breaking into the line through coupling joints. When a blockage occurs, the waste water backs up into the sink or toilet. A plunger is often the simplest option to remove the blockage, though if that option doesn't solve the problem, try using a flexible sewer snake (known also as an auger) by inserting it into the sewer line.

Start addressing the backup issue with a plunger.
  1. Place old towels on the bathroom floor around the base of the toilet, in case of spillages. Position the rubber head of the plunger face down in the base of the toilet bowl, or around the drain hole in the base of the sink. In both cases, ensure that the plunger's head is beneath the level of the wastewater.
  2. Push down on the plunger's handle to force water into the sewer line. This will hopefully force the blockage out of position. Repeat this several times. Look for the lever of water in the toilet bowl or sink to lower. If it does not, use a sewer snake.
  3. Pull 4 feet of flexible hose out of the sewer snake's casing, and feed it into the bottom of the toilet bowl. If working on a sink blockage, place a bucket under the P-trap (located under the sink) and unscrew the nuts on each side of the P-trap's bend, by hand. Remove the trap's bend. Push the first 4 feet of sewer snake into the sewer pipe coming out of the wall that the P-trap was attached to.
  4. Turn the handle on the sewer snake's casing, to rotate the flexible hose inside the sewer line. Push 2 feet more of hose into the sewer pipe, and rotate again. Repeat this two-fold procedure until the flexible pipe is fully inserted into the sewer line. Rotate the hose again, then slowly pull the hose out of the sewer line, rotating it every 2 feet.
  5. Wipe off the hose with a rag before inserting it back into its casing.
  6. Replace the P-trap's bend by tightening the two nuts by hand. Flush the toilet, or run water into the sink to help flush away all remnants of the backup and blockage in the sewer line.

Things You Will Need

  • Old towels
  • Plunger
  • Sewer snake
  • Bucket
  • Rag


  • After taking off the P-trap's bend, take a quick look inside the bend to make sure the blockage isn't existing there. If it is, remove the blockage with a wire.

About the Author

Steve Sloane started working as a freelance writer in 2007. He has written articles for various websites, using more than a decade of DIY experience to cover mostly construction-related topics. He also writes movie reviews for Inland SoCal. Sloane holds a Bachelor of Arts in creative writing and film theory from the University of California, Riverside.

Photo Credits

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