How far must the center-to-center distance be between adjacent fixtures, like water closets, as per code requirements?

The requirement for the center-to-center distance between adjacent fixtures, such as water closets, is established to ensure adequate space for users and proper functioning of the fixtures. The correct answer of 30 inches aligns with the guidelines in the International Residential Code (IRC), which emphasizes that residential plumbing installations must accommodate the practical needs of individuals without compromising accessibility or safety.

Having a minimum distance of 30 inches between the centers of fixtures allows enough room for a person to comfortably use each fixture while also facilitating maintenance and cleaning. This standard helps prevent overcrowding in smaller bathrooms and ensures compliance with usability standards, making the space more functional and user-friendly.

While shorter distance options may seem practical in some cases, they can lead to cramped conditions, making it difficult to access one fixture without interfering with the other.