Booster Chlorination in Palestinian Schools: Field Investigation of Chlorination Dynamics in Central Hebron Directorate

Intermittent water supply is common in Palestine, prompting schools to rely on on-site water storage systems, including underground and roof tanks. Prolonged and uncontrolled water storage leads to quality degradation, especially with free residual chlorine (FRC) depletion. Hence, this poses health risks to students and staff. This pilot (field) study evaluated the effectiveness of booster chlorination under the current storage conditions to optimize and improve the existing chlorination process. Four schools were selected based on the type of water storage systems (two with underground tanks, two with roof tanks) and building age. Booster chlorination was applied at two chlorine doses (0.5 mg/L and 1 mg/L). FRC was monitored until levels dropped below 0.05 mg/L. Results show that the currently applied chlorine dose (0.5 mg/L) is insufficient to reach the minimum national FRC standard (0.2 mg/L) after 30 min. In contrast, a 1 mg/L chlorine dose is more effective in maintaining the minimum FRC concentration limit for a longer time. In addition, manual mixing is ineffective in large underground tanks, while it is effective in roof tanks. This study urges the need to revise the national chlorination guidelines and to adjust chlorination practices to ensure safe drinking water in schools.