What is the minimum size of access opening required for a backwater valve installed less than 24 inches deep inside a building?

The minimum size of access opening required for a backwater valve installed less than 24 inches deep inside a building is 24 inches by 24 inches. This dimension is specified to ensure easy access for maintenance, repair, and inspection of the backwater valve.

The 24 x 24 size accommodates not only the valve itself but also allows enough room for a technician to maneuver tools and perform necessary work without compromising safety or efficiency. Access openings are critical in plumbing systems, especially for components that may require regular intervention, like backwater valves, which play a vital role in preventing sewage backflow into buildings. Proper access size is essential for maintaining the plumbing system and ensuring compliance with plumbing code requirements.

Other options, like 12 x 12 or 12 x 14, are insufficient in size to allow for the necessary access, and a 10 x 10 opening would be too restrictive for any practical maintenance work, making them unsuitable for this particular installation requirement. Therefore, the correct choice highlights the importance of adhering to the specified code to facilitate proper plumbing maintenance.