What is the minimum surface height above the drain inlet required for shower compartments and walls above bathtubs with installed shower heads?

The minimum surface height above the drain inlet for shower compartments and walls above bathtubs with installed shower heads is primarily determined by the need to prevent water from splashing out and to ensure effective drainage. A height of 72 inches is typically recognized as providing adequate coverage to contain splashes and falls from spray, ensuring that water from the shower head stays directed within the confines of the shower area or bathtub.

This standard is based on both practical use and building codes that seek to reduce the risk of water damage to the surrounding area, as well as enhance the user's experience by providing sufficient height for most users. The standardization at this height also helps align with industry practices that prioritize both functionality and user safety in wet areas of a building.

Higher options, while they may seem reasonable, exceed common requirements and may not be necessary for effectively managing water within these spaces. Therefore, 72 inches is the correct minimum height.