Sewer System Basics

Every plumbing fixture in your home is joined by the same drainpipe, including the kitchen sink, the dishwasher, the clothes washer, the toilets, and so on. The waste from each of these fixtures exits the house through this one drainpipe. A problem caused by one fixture can easily become a problem for all the other fixtures.

Your common, everyday household sanitary sewer system consists of three basic elements:

• The waste lines and drainpipe: The waste lines carry sewage from each of the fixtures in your home down through the walls and under the floor then outside the home to either a public sewer system beneath the street or a septic tank somewhere below ground on your property. A clog in any of these pipes stops waste from reaching its destination away from your home -- and it can back up into your home.
• The vent pipes: Vent pipes travel from each plumbing fixture (or group of plumbing fixtures), upward (inside walls) and out through the roof. These are the black pipes on top of your roof. The vents allow air into the sewer lines so that they drain freely. A clogged vent pipe can be a serious problem, preventing good drainage of the waste.
• The p-traps: You have one of these traps in every fixture: sink, toilet, washing machine, you name it. If the fixture drains into the sewer system, the water or waste first travels through a p-trap. The trap allows water and waste to enter the sewer system while at the same time preventing sewer gases from backing up into the house. A clogged p-trap can inhibit the flow of waste from the home and can allow stinky gases to back up into the home through the fixtures.