What should the water clarity allow for visibility?

The correct response indicates that the main drain should be visible from the pool deck, which is critical for ensuring a safe swimming environment. This visibility is a key indicator of proper water clarity. When the main drain can be seen clearly from the edge of the pool, it demonstrates that the water has been sufficiently filtered and treated, meeting health department standards.

This requirement is in place to help pool operators and lifeguards monitor the pool for any potential hazards, such as debris or emergency situations, without having to enter the water. Clear visibility of the main drain also reflects adequate water circulation and chemical balance, preventing issues related to water quality that could affect swimmers' health and safety.

In contrast, visibility from the stairs or the surface may not provide the same level of assurance regarding the overall clarity of the pool. Being visible only when underwater does not meet safety standards, as it does not allow for proper surveillance of the swimming area by personnel on the deck. Therefore, ensuring visibility of the main drain from the pool deck is a fundamental requirement for pool operation and safety.