What is the main function of a back vent pipe?

The main function of a back vent pipe is to prevent sewer gas from entering the home. This is critical for maintaining indoor air quality and ensuring the safety of the occupants. Back vent pipes help to equalize pressure in the drainage system, which prevents siphoning of water from traps in fixtures. When water is drawn out of a trap, it creates a vacuum that can pull sewer gases into the living space. By providing a route for air to vent the system, these pipes help to ensure that the traps remain filled with water, effectively blocking any harmful gases from seeping into the home. This function is essential for any plumbing system to work safely and efficiently, directly contributing to the health and comfort of the building's inhabitants.