What Causes the Sewer to Back Up Into the Toilet & Drains?

Home Plumbing

• All the plumbing fixtures, such as sinks, bathtubs and toilets, are tied together into your plumbing system. Pipes, generally about 1 1/2 inches in size, lead from the sink or bathtub into a larger pipe called a stack. Toilets typically are connected to the outlets on each of the stack branches. The stacks, in turn, lead into the sewer main that carries the sewage away from your house into a municipal sewer system or a septic system.

Sewer Stoppages

• If your sewer is backing up into your toilet and drains in different locations of your house, the problem isn't just a localized blocked up pipe but most likely a stoppage in the main sewer drain line. Because the entire line is clogged, using a sink in an upstairs location, for example, will cause a backup in all of the other plumbing fixtures in the house. This can be bad if it is not taken care of quickly. On the other hand, because you know where the blockage is, you can respond to the situation rapidly.

Sewer Main Setup

• The main line for the sewer leads from your home to where it ties into a larger municipal or septic system. Sewer lines usually are buried two feet or deeper in the ground, although this can vary by location. At either end of the main, sometimes both, is a cleanout plug, which leads from the sewer main up through the ground and usually lies about three or four inches above the surface of the lawn or yard. A raised square nut on the surface of the plug allows wrenches to grasp the plug for removal.

Sewer Backup Causes

• There are a number of different reasons why a sewer main line can clog. Foreign objects, such as washcloths, accidentally flushed down the toilet, can lodge in the sewer line or tree roots can grow into the line in search of water. The latter happens frequently with older clay sewer pipes.

Clearing a Sewer Backup

• The easiest way to clear a sewer backup is by renting a machine called an electric plumbing snake. These machines feature a long snaking cable topped by a pair of jaws for cutting through clogs. Remove the plug cover with a wrench and insert the end of the snake into the sewer main. Turn on the snake and slowly feed it through the line until it meets the clog. Reverse direction of the snake, then resume pushing the snake forward with your hands. Repeat this process until you can feel the clog break up. Test by flushing your toilet or running water in the sink to make sure it flows freely.