Characterizing Supply Variability and Operational Challenges in an Intermittent Water Distribution Network

Abstract

Intermittent piped water supply is common in low- and middle-income countries and is inconvenient for users, particularly when supply schedules are unreliable. In this study, supply schedules and operational challenges were characterized in intermittent areas of the Arraiján, Panama distribution network based on one year of pressure and flow monitoring in four study zones, analysis of three years of pipe break data, and observations of system operation. Service quality was found to vary among users and supply schedules were often irregular and unpredictable. Direct causes of unanticipated supply outages included pump failures, chronic pipe breaks in specific parts of the system, transmission main breaks, irregular valve operations, and treatment plant outages. The extent and duration of these outages were often increased by high rates of water loss, insufficient storage capacity, and difficulty detecting and resolving infrastructure failures. Factors associated with intermittent supply, such as intermittent pumping, appeared to be associated with a higher frequency of pipe breaks. However, the analysis did not indicate a strong general correlation between intermittent supply and pipe breaks. Pressure and flow monitoring in intermittent supply areas, similar to that undertaken in this study, could be a valuable tool to improve regular operations as well as longer-term planning and prioritization of system improvements. Water loss reduction and adequate distribution storage capacity could also mitigate the effects of operational failures. Investments in monitoring and data analysis have the potential to improve the reliability of intermittent supply in cases where continuous supply is not immediately feasible.

Bacterial communities in a neotropical full-scale drinking water system including intermittent piped water supply, from sources to taps

“…While most of the DWDS in Arraiján provided continuous water supply, several zones operated intermittently. 12,17 In addition, the DWDS suffers from around 40% water loss due to pipe failures, illegal connections, and other factors ( e.g. , loose fittings).…”

“…1b and c). 12,17,49 These treatment plants sourced their water from the Panama Canal Watershed, primarily from Lake Gatún, which is recharged by the Chagres River, and lake Miraflores (both artificial lakes used in the operations of the Panama Canal). Conventional surface water treatment was practiced, with slight differences between plants (ESI † Table S1; at DWTP A and B, free chlorine was applied upstream of filtration).…”

“…While most of the DWDS in Arraiján provided continuous water supply, several zones operated intermittently. 12,17 In addition, the DWDS suffers from around 40% water loss due to pipe failures, illegal connections, and other factors (e.g., loose fittings). 15 To assess the effects of treatment, piped distribution, and IWS, the drinking water system of Arraiján was sampled between December 2016 and February 2018 (ESI † Table S2).…”

“…2–5 Intermittent water supply (IWS) is a common practice in LMICs and refers to water supply to consumers for less than 24 hours per day on average. 6 IWS impacts over one billion people around the world, causing public health risks, such as diarrheal infections, and difficulties to consumers and water utilities; 7–12 yet, due to water scarcity and climate change, this practice is expected to increase. 8,13…”

“…[2][3][4][5] Intermittent water supply (IWS) is a common practice in LMICs and refers to water supply to consumers for less than 24 hours per day on average. 6 IWS impacts over one billion people around the world, causing public health risks, such as diarrheal infections, and difficulties to consumers and water utilities; [7][8][9][10][11][12] yet, due to water scarcity and climate change, this practice is expected to increase. 8,13 Several characteristics of IWS have the potential to increase the deterioration of drinking water quality compared to continuous supply systems, including: 1) microbial growth in bulk water, pipe-wall biofilm and loose deposits while water is drained or stagnant between supply, and subsequent flushing and detachment of microorganisms when supply restarts (known as first flush); 2) intrusion and backflow of contaminants via pipe leaks, loose fittings and/or customer connections during periods of low or negative pressure; and 3) recontamination and microbial growth during household storage.…”