At what height above finished floor should a cleanout be installed above a water closet?

The cleanout for a water closet should be installed at a height of 42 inches above the finished floor. This height is specified in plumbing codes to ensure that the cleanout is accessible for maintenance and inspections while also being at a level that does not interfere with normal bathroom usage.

Installing the cleanout at this standard height allows for ease of access for plumbers, preventing potential issues with clogs and facilitating necessary cleaning and inspections of the drainage system. In addition, it helps to maintain a consistent standard across installations, ensuring that all plumbing fixtures can be serviced uniformly.

The other height options listed may not provide the same level of accessibility or adherence to code requirements, which is why 42 inches is recognized as the appropriate standard.