Swimming Pool Main Drain

Main drains are an essential pool plumbing feature necessary to ensure thorough water circulation and sanitation. The now standard anti-vortex main drain design has increased its safety and utility. There are generally two types of main drains based on their design and functionality:

Single Main Drain

This type consists of a single suction point at the deepest point of the pool. The anti-vortex main drain design has made single-drain pools safe for swimmers The domed anti-vortex main drain design allows water to pass through even when it’s partially blocked.

Before the Virginia Graeme-Baker (VGB) Act, residential pools were usually built with a single main drain. The single main drain design coupled with the pre-anti-vortex style drain grates meant swimmers became entrapped, causing drowning or physical bodily harm,

Dual Main Drains

Newer pool designs now incorporate at least two round 8-inch wide anti-vortex main drains or multiple 32-inch channel main drains for safety and water flow efficiency. The channel drains also feature an anti-vortex design. These drains are placed a specific distance apart (relative to pool size) to mitigate the risk of entrapment. The idea is that if a swimmer were to cover one drain, the other would still allow water to flow. 

Before installing safety equipment such as anti-vortex main drains, consult local building codes and safety regulations to ensure compliance with the latest safety standards.