A square main drain is a type of pool main drain featuring a square-shaped drain cover or grate installed at the deepest part of a swimming pool floor. Like other main drains, its primary function is to draw water from the pool’s bottom and direct it toward the filtration and circulation system, helping to ensure thorough water turnover and removal of heavier debris that settles at the bottom. The square design of the drain cover often provides a larger surface area for water intake compared to smaller or round drains, which can enhance drainage efficiency and reduce suction pressure on any single point, improving safety. Square main drains are usually made from durable, corrosion-resistant materials such as stainless steel or heavy-duty plastic, designed to withstand pool chemicals and constant water flow. In addition to its functional role in water circulation and debris removal, the square main drain typically incorporates safety features such as anti-entrapment grates or covers that comply with regulatory safety standards, reducing the risk of swimmer entrapment or injury. Overall, a square main drain is an effective and safe component of a pool’s hydraulic system, contributing to balanced water circulation, cleanliness, and swimmer safety.