For an employee toilet room, the required lavatory shall be _____ the required water closet.

In the context of plumbing installations within employee facilities, it is important to consider accessibility and convenience for users. The correct answer indicates that the required lavatory must be in the same room as the required water closet. This arrangement promotes efficient use of space and ensures that users have easy access to handwashing facilities immediately after using the toilet, adhering to health and hygiene standards.

Placing the lavatory close to the water closet minimizes the time and effort required for employees to wash their hands, which is critical in maintaining hygiene in a workplace. This proximity not only enhances user experience but also aligns with plumbing codes that focus on effective design and functionality in restroom facilities.

The other choices do not support this level of accessibility and convenience. For instance, a separation by a partition could hinder quick access to handwashing, while specified distance requirements do not prioritize the practical relationship between the two fixtures as effectively as having them in the same room. Thus, ensuring that both the lavatory and the water closet are in the same room supports a higher standard of restroom design that prioritizes user needs.