The Effects of Intermittent Drinking Water Supply in Arraiján, Panama
Over three hundred million people throughout the world receive supply from piped drinking water distribution networks that operate intermittently. This dissertation evaluates the effects of intermittent supply on water quality, pipe damage and service reliability in four study zones (one continuous and three intermittent) in a peri-urban drinking water distribution network in Arraiján, Panama. Normal water quality in all zones was good, with 97% of routine water quality grab samples from the distribution system and household taps having turbidity < 1 NTU, total coliform and E. coli bacteria concentrations < 1 MPN / 100 mL, and ≥ 0.3 mg/L free chlorine residual. However, negative pressures that represent a risk for contaminant intrusion and backflow were detected in three of the four study zones, and water quality during the first flush when supply resumed after an outage was sometimes degraded. High and transient pressures that could cause pipe damage were detected in study zones with intermittent pumping, but filling and emptying of distribution pipes due to intermittent supply was not associated with transient or extreme pressures. Operational challenges, including frequent infrastructure failures, difficulty monitoring the network, and a lack of system information, resulted in unreliable supply in the intermittent zones. Continuous pressure and flow monitoring methods used in this research could be helpful tools for operators of intermittent distribution networks to provide more reliable service and identify hydraulic conditions that could lead to contaminant intrusion or pipe breaks.