What action should be taken if the main drain is not secure?

Closing the pool immediately is the appropriate action if the main drain is not secure. The main drain is a critical safety component of the pool's circulation system. An unsecured main drain poses significant safety risks, including potential entrapment hazards, especially for swimmers. By closing the pool, you mitigate these dangers and ensure that patrons are not exposed to the risks associated with an unstable or malfunctioning drain system.

Taking this action allows pool operators to assess and address the issue without compromising swimmer safety. Other approaches, such as placing warning signs or notifying patrons to swim carefully, do not provide an effective solution to the underlying problem of an unsecured main drain. Continuing to operate the pumps could exacerbate the situation, as compromised drainage can lead to further complications. Therefore, closing the pool immediately is essential for maintaining a safe swimming environment.