When expanding water facilities, what should be capable of impounding at least the total?

The correct response is that the facilities must be capable of impounding at least the total daily flow. This requirement ensures that the system can manage the maximum expected water usage effectively, including peak times when daily consumption spikes.

By designing the system to handle daily flow, it allows for immediate access to necessary water resources, preventing shortages and ensuring reliable supply for consumption, distribution, and emergency readiness. It also aids in managing water quality, as stagnation in facilities can lead to contamination or degradation of water standards if there is not sufficient turnover.

In contrast, focusing on longer time frames such as weekly, biweekly, or monthly flow does not provide the immediate responsiveness needed for daily variations in water demand. This could lead to situations where the supply is insufficient to meet daily needs, especially in operational contexts where water usage can fluctuate significantly from day to day.