A unified probabilistic energy and carbon footprint appraisal for intermittent water supply systems in arid regions

A probabilistic methodology assessed hydraulics, water consumption, distribution pumping, and households pumping from the ground to rooftop storage for energy consumption in 24/7 and 2-day supply scenarios in two distribution networks, each with 379 and 959 service connections and diverse topographies. A local market survey gathered the characteristics of thirty-two household-level pumps used in the area. Considering a per capita daily water consumption of 250 L, probabilistic analysis revealed that the daily operating time of household pumps varied from 0.155 to 0.17 h at the median and from 0.37 to 0.47 h at a 0.9 probability, highlighting variation in household sizes within the study region. The study observed 26% higher energy consumption with a 24/7 supply compared to a 2-day supply for the average household size of 5.6 persons. The 2-day supply exceeded the 24/7 energy requirement for households larger than 8.7 (exceedance probability of 0.1), due to the longer operational hours. Sensitivity analysis identified the household pump's operating time as the most critical contributor to the intermittent supply's energy. Considering the consumers' concerns on water quality in the realistic case, the study found ~ 60% higher energy (0.069 kWh/person/day) and carbon emissions (18.45 kg CO₂ eq/person/year) for 35% consumers using a household-level purifier, 60% bottled water, and 5% trusting in supplied water in comparison to a 24/7 supply. Instead of controlling water loss through intermittent supply, a shift to continuous supply with proactive maintenance can compensate for the additional costs by providing better water quality, satisfied customers, and a reduced global energy and carbon footprint for water supply systems in arid regions.