What is the proper detention time for disinfecting a water storage tank with a free chlorine level of 10 mg/L?

The proper detention time for disinfecting a water storage tank with a free chlorine level of 10 mg/L is 24 hours. This timeframe is generally recognized in industry standards to ensure effective disinfection of water storage facilities. Disinfection processes require sufficient contact time for the chlorine to effectively kill pathogens and other microorganisms present in the water.

Having a chlorine concentration of 10 mg/L is relatively high, which supports the efficacy of disinfection. However, to achieve maximum effectiveness, allowing for a full 24 hours ensures that the chlorine has ample time to interact with any potential contaminants. Insufficient contact time could result in inadequate disinfection, thus posing a risk to water quality and public health.

Detention times longer than 24 hours, while sometimes advocated in scenarios of extreme contamination or for specific disinfection procedures, are not standard for typical chlorine disinfection in water tanks at this concentration. Shorter times than 24 hours may not guarantee enough reduction of pathogen levels, highlighting the importance of the 24-hour period as a balance between effectiveness and practicality for routine disinfection.