Are Sewer Pipes Safe in the Attic?

About Sewer Pipes

• Sewer pipes are referred to in plumbing as being part of the drainage, waste and ventilation system, or DWV. DWV pipes are usually made out of ABS plastic, which is similar to PVC except that it's thicker and better resists the corrosion that's often associated with raw sewage. DWV pipes are connected using a special type of chemical cement that bonds the plastic together permanently. In limited applications, ABS and PVC glue can be used to join transitions between the two materials.

DWV Requirements

• DWV pipes can be installed in almost any place in your home. The ABS plastic pipes that are part of the sewage system can also be safely installed inside an attic. The only reason to install sewage pipes inside an attic, however, is if there is a source, such as a toilet, in the attic that requires a drain. Sewage pipes, like most plumbing systems, require gravity to pull waste out of the system. This means that sewer pipes can not be installed in the attic if the source of the waste is lower in the system.

DWV Testing

• It's critical that all sewer pipes are sealed watertight with permanent bonds between pipes. The seals are important because raw sewage produces methane and other gases that can be harmful to human health if released into the air. For this reason, it's important to pressure test your DWV system after installation and again once every five years. Pressure testing by a professional plumber ensures there are no gaps in the seals and that dangerous gases remain inside the DWV system.

DWV Maintenance

• Most DWV pipes have a threaded plug. These are known as cleanout plugs. Removing a cleanout plug gives you angled access to the pipe just below where it connects to fixtures such as toilets or drains. This opening provides access for removing any debris clogs. It also provides a place for installing a pressure test cap while conducting a pressure test of the pipes. When not in use, cleanout plugs should be tightly screwed into the pipe to prevent leaks.