What type of pipe is used to ventilate a house drainage system to prevent gray siphonage?

Vent pipes play a crucial role in a house drainage system by maintaining proper air pressure within the pipes. Their primary function is to prevent siphonage, which can occur when water is drained from fixtures. When a fixture discharges wastewater, it can create a vacuum that may siphon water from the traps of other fixtures, leading to potential sewage gases entering the living space and allowing harmful odors or bacteria to infiltrate the home.

By drawing in air, vent pipes help to equalize pressure, preventing the traps from losing their water seals. This not only protects against unpleasurable odors and potential health hazards but also ensures that wastewater can flow smoothly through the drainage system without obstruction.

Drain pipes are used to transport wastewater from fixtures to the sewer system, supply pipes deliver potable water to fixtures, and overflow pipes are designed to prevent overflow in tanks or containers. While all of these pipes have essential functions, they do not address the specific need to ventilate the system to mitigate siphonage, which is why the correct answer is focused on vent pipes.