What Is the Main Drain?

The main drain is a plumbing component that many inground swimming pools use to help filter the pool’s water. While it’s called the main drain, this component doesn’t drain anything. Instead, it sucks water into the filter so it can be cleaned and recirculated. 

Main drains are located on the side of the pool that houses the plumbing components. The drain is installed as low as possible, as that’s where most particulate matter settles in a swimming pool.

The alternative to the main drain is a downward-pointing return, which forcefully directs water from the filter down into the pool to help agitate particulate matter and improve filtration.