How to Plug the Bottom Main Drain in an Inground Pool

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Plug your inground swimming pool's main drain to prepare for winter.

An inground swimming pool's main drain is located in the deep end of the pool. A main drain circulates the pool's water by pulling water off the bottom of the pool and sending it to the filter. During winter months or periods of non-use, most pool drains do not need to be plugged, but in some cases plugging a main drain is required or recommended. Plugging a main drain shuts off the suction caused by the drain and prevents water from traveling through the lines connected to the drain.


Step 1

Lower the water level of the inground swimming pool so the main drain is easily reachable. Drain the water completely during colder months. Ensure all pool equipment is turned off.

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Step 2

Use a screwdriver to unscrew any screws around the lip of the main drain lid. Pull gently up on the lid until it pops out of place.


Step 3

Locate the small hole at the bottom of the main drain. This is the plumbing line to the filter. Plug the small hole with an expandable rubber plug or a plastic threaded plug, if the hole is threaded. Replace the main drain lid if needed.



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