Main drains are submerged suction outlets that are located on the bottom of a pool and are used to move water to a recirculation pump. Main drains consist of a cover, a mounting frame, a sump pump and fasteners. After a pool has been dug and its frame has been erected, the pool main drain is ready to be installed.
Find the lowest point on the pool floor. Mark it with a stake. This is where the main drain is going to be installed. Measure the size of the drain body, and dig a hole to accommodate its dimensions in the area where the stake was placed.
Take a shovel and draw a straight line in the dirt that leads from the main drain and goes one foot out past the bottom pool frame rail, near where you are going to place pipes that will go to the pool filter. Dig a 12-inch deep trench out of the line.
Lay the 1 1/2 inch PVC pipe into the trench. Paint the end of the 1 1/2 inch PVC pipe that sticks out past the pool frame and the inside of 1 1/2 inch elbow where they are going to connect with PVC cement or glue. The top of the elbow should face up toward the pool filter. Insert the 1 1/2 PVC elbow into the end of the PVC pipe. Paint the other end of the 1 1/2 inch PVC elbow with PVC cement and then place a 1 1/2 inch PVC pipe into the top of the elbow. Attach the pipe to the pool filter.
Set the drain body with the its cover attached down into the trench. Insert the end of the PVC pipe into the hole at the bottom of the drain body's side wall. Fill in the trench with dirt. Rake the pool bottom smooth once again.
Glue the bottom gasket of the main drain to the top of the drain. Install the pool liner. Place the second gasket, face plate, and grille onto the drain. Add the faceplate and gasket, then cut the drain opening into the liner with a box or liner knife.
Fill the pool bottom with 6 inches of water. Insert the main drain screws by pushing them through the liner and then tightening them to the drain.