During normal operations, what percent of water is typically removed by the drain in swimming pools?

In swimming pool operations, it is typical for around 20 percent of the water to be removed by the drain during routine maintenance and operations. This percentage allows for effective cleaning, chemical balancing, and replacement of water that may have become contaminated or degraded over time. Maintaining this level of water turnover is essential for ensuring the quality of the pool water, supporting proper filtration, and preventing the accumulation of pollutants.

The other percentages provided in the choices are below or above the amount commonly seen in practice, as they do not align with standard operational practices for swimming pool maintenance. A 10 percent or 15 percent removal might not be sufficient to adequately maintain water quality, while a 25 percent removal would represent an excessive volume of water being drained, which could be inefficient and unnecessary for regular operations. Therefore, the 20 percent figure is widely accepted as the norm in the industry.