Which condition is not a requirement for the storage of water in tanks?

The correct choice highlights that having a disinfectant demand is not a requirement for the storage of water in tanks. While it is essential for water storage systems to maintain a certain level of disinfectant residual to ensure that the water remains free of harmful pathogens, the concept of disinfectant demand refers to the amount of disinfectant that is consumed by various substances present in the water, such as organic materials or sediments.

In practical terms, water storage systems focus on ensuring structural support, regular inspections, and maintaining an appropriate disinfectant residual to guarantee water quality and safety. Disinfectant demand is more about understanding how much disinfectant is necessary to achieve desired water quality, rather than a direct requirement for the design or functionality of water storage tanks themselves. Therefore, it is not listed as a condition necessary for the actual storage structure.