How far apart should water closets be set from the center of one fixture to the center of another?

The correct distance for setting water closets apart from the center of one fixture to the center of another is 30 inches. This measurement aligns with plumbing code requirements, which aim to ensure safety, comfort, and functionality in restroom design.

By having a distance of 30 inches between fixtures, adequate space is provided to allow users to access each water closet comfortably without feeling cramped. This distance also helps in maintaining proper drainage and plumbing installation, ensuring that each unit can operate effectively without interference from the other. Additionally, having this standardized measurement helps in planning and designing restrooms to be compliant with accessibility standards, which is crucial in public and commercial spaces.

In contrast, other distances either provide too little room, which can lead to functional difficulties and user discomfort, or excessive distance, which is generally not necessary for effective use and could be impractical in a standard restroom layout. Thus, the choice of 30 inches is both practical and in compliance with established guidelines, making it the most appropriate answer.