For the effective operation of an HTSS, what is essential concerning the holding tank?

For the effective operation of a Holding Tank System (HTSS), it is essential that the holding tank must have no overflow allowed except in specific conditions. This is critical because any overflow can lead to environmental contamination and violation of health regulations. The design of the system aims to ensure that all wastewater is contained within the tank until it can be pumped out for treatment or disposal. Allowing an overflow undermines the system's integrity and can cause serious ecological and sanitary issues.

The requirement that overflow is not allowed, except under specific conditions, helps maintain the quality of surrounding water sources and prevents the release of untreated waste into the environment. Such regulations are important to protect public health and the environment.

In contrast, the other options suggest practices that would compromise the purpose and effectiveness of the holding tank. Maintaining a permanent overflow would lead to constant contamination. Connecting the tank to storm drains would improperly mix wastewater with stormwater, causing significant environmental risks. Lastly, while having a tank large enough to avoid regular pumping may seem beneficial, it does not address the fundamental requirement of preventing overflow, which is the key to operating an HTSS effectively.