What is the purpose of a vent pipe in plumbing?

The purpose of a vent pipe in plumbing is to allow sewer gases to escape. Vent pipes serve a crucial role in maintaining the proper functioning of the drainage system. They equalize air pressure in the plumbing system, which helps prevent the creation of vacuum conditions that could impede the flow of wastewater. By allowing sewer gases to vent outside, these pipes also help to protect the health and safety of the living environment by preventing harmful gases from entering the home.

Additionally, vent pipes assist in maintaining the trap seals of the fixtures. This is important because trap seals prevent sewer gases from entering the home through the drains. Without adequate venting, traps could be siphoned dry, leading to the unpleasant and potentially hazardous situation of sewer gases infiltrating the living space.

In contrast, other options do not accurately describe the function of a vent pipe: it does not increase water pressure, drain excess water, or connect fixtures to the main sewer line. Each of these functions is attributed to other components of the plumbing system, highlighting the distinct and vital role of vent pipes in ensuring safe and effective drainage.