What is a wet vent in bathroom plumbing?

A wet vent is a plumbing pipe that serves dual purposes - it carries wastewater from one fixture while simultaneously providing ventilation for other fixtures in the bathroom. This is different from a dry vent, which only carries air and gases.

In a typical bathroom wet vent setup, the lavatory (bathroom sink) drain acts as the wet vent for the toilet. The sink's drain pipe extends upward to connect with the main vent stack, and along the way, it receives the toilet's waste line. This means the same pipe that drains your sink also vents your toilet, allowing proper drainage and preventing siphoning of trap seals.

Wet venting is particularly useful in bathroom renovations where space is limited or where running separate vent lines would be difficult or expensive. It's commonly used when fixtures are grouped together, such as a toilet and sink on the same wall. The Ontario Building Code allows wet venting under specific conditions, including proper pipe sizing and fixture arrangements.

The key advantage is cost and space savings during installation, as you need fewer pipes running through walls and up to the roof. However, wet vents must be properly sized - typically larger than standard drain pipes - to handle both drainage and venting functions effectively. The lavatory serving as the wet vent must be upstream of the toilet in the drainage system.

Installation requirements in Ottawa follow Ontario Building Code specifications for pipe sizing, slope, and fixture connections. Since wet venting involves complex code compliance for proper drainage and venting, it's typically handled during professional bathroom renovations where licensed plumbers ensure all connections meet current standards.

For bathroom renovation projects involving wet venting, a building permit is required in Ottawa, and the work should be completed by licensed professionals who understand the specific code requirements for wet vent installations.