What action is taken after 24 hours of disinfecting a water tank?

After 24 hours of disinfecting a water tank, the appropriate action is to allow the chlorine concentration to decrease to 2 mg/L. This is a standard practice in the disinfection process, ensuring that the levels of chlorine are appropriate for safe consumption and do not adversely affect water quality or taste.

Maintaining a residual chlorine concentration of around 2 mg/L after disinfection helps to ensure that any remaining pathogens are effectively managed while still allowing for safe water usability. This concentration is generally considered effective in maintaining microbial protection throughout the water distribution system.

Other actions, such as increasing the concentration, would not be appropriate after the initial disinfection period, as it could lead to excessive levels of chlorine that might be harmful. Emptying the tank would disrupt the water supply and could introduce contaminants, while refilling the tank does not directly relate to the immediate post-disinfection protocol regarding chlorine levels. The focus on maintaining a specific chlorine residual is key to ensuring both safety and effectiveness in water treatment practices.