A floor drain is a plumbing fixture that is installed in the floor of a structure, mainly designed to remove any standing water near it. They are usually round, but can also be square or rectangular. They usually range from 2 inches to 12 inches, most are 4 inches in diameter. They have gratings that are made of metal or plastic. The floor around the drain is also sloped to allow the water to flow to the drain. Most residential basements have 1 or more floor drains, usually near the water heater or washer/dryer. They can also be found in commercial basements, restrooms, kitchens, refrigerator areas, locker/shower rooms, laundry facilities and near swimming pools, among other places.
A floor drain should always have a strainer secured over it to prevent injury, entry of foreign objects, or introduction of unwanted pests into the facility. However, if the strainer is not smooth enough, hair and other objects can still get stuck in it, clogging the drain.