How a Flush Toilet Works
The Drain, Waste, Vent System
Unseen and hidden in the walls of your home is a most important part of the flushing cycle of a toilet. It is the complex network of pipes called the Drain-Waste-Vent system (DWV). The DWV drains the water that carries the waste away, and it vents the system to the atmosphere above a building. You have probably seen the short vent pipe(s) sticking up on your roof; one is usually found directly above where a toilet(s) is located in the house below. Odors and sewer gases are allowed to escape through this pipe, but equally important, atmospheric pressure enters the system and prevents a vacuum from forming when water fills the pipes and drains through the system.
Before the venting of a plumbing system came into being, plumbing was a hazardous occupation due to the possibility of explosion from the sewer gases that accumulated in the system.
The vent pipe can become clogged with the bodies of small animals or birds; birds build their nests on and in these pipes, and debris can collect around the connections to the fixtures that drain into the pipe. A clogged vent pipe creates a retarded flow that is often the cause of illusive flushing problems. Some of the symptoms of a clogged vent line are such things as gurgling sounds in bathroom fixtures when other fixtures are draining, a lazy flushing toilet, or a toilet that appears to be stopped up, but doesn't respond to plunging or the use of a snake.
The solution to a clogged vent line is to run a snake down through the pipe
from the roof. At best, a tricky job requiring that you climb around on your roof with a big drain snake. A job that IMHO is best left to a professional plumber who has the right equipment and experience. A friend of mine decided to use his garden hose to clear a clogged vent much to his regret. It might have worked, had he not turned the water on. When he turned the water on, the water erupted through all the drain openings inside the house, presenting him with quite a cleanup job.
Genova Products, Inc., a leader in the do-it-yourself plumbing industry since 1962, has published a number of brochures on plumbing that are free to download from their site. The illustration to the right is a small version of
one of the illustrations found in their four-page brochure on the DWV system titled, Facts on Genova Vinyl DVW Systems. Genova also has published a do-it-yourself guide to plumbing.
The Genova idea of using plastic piping for residential Drain, Waste, and Vent systems has become the accepted way to install plumbing and is found in virtually every U.S. home built today. The history of Genova Products, Inc. makes for very interesting reading.
"How a Toilet Works" continues on
See Anatomy of a toilet for more details.
What makes a toilet bowl flush?