Mechanisms and Policies to Encourage Water Efficiency among Scottish Water Customers
Scottish Water is the publicly owned provider of water and wastewater services in Scotland. Scottish Water supplies 2.3 million household customers (880 ML served daily) and 170,000 non-household customers (465 ML/day). Motivated by the water efficiency duty set by the Scottish Parliament, this research analyzed the potential impact of water efficiency measures on households in Scotland. It also considered the wider sustainability implications of water efficiency.
Household water consumption in Scotland is driven by the largest demongraphic ('traditionally comfortable') by ACORN classification. The wealthier classes ('older prosperity' and 'affluent families') use the most water per household at nearly 400L/HH/Day compared to the lowest of 260L/HH-day for 'City Lifestyle' households. Three demographic groups (27% of households) may not be able to reduce their consumption to below 130 L/person/day by water efficiency alone.
Water efficiency programs and implementation results are compiled and analyzed from the USA, Australia and England. These case studies inform analysis applied to Scotland. A nationwide Scottish Water water-efficiency intervention on toilets, showers, and taps could result in reducing household water demand by 15%, at a cost of £332M. It would reduce energy use by nearly 1 GWh/year and annual carbon emissions by 208 tCO2e - approximately 44% of the size of Scottish Water's current operational footprint.
Alternatively, a single measure to distribute low-flow showerheads could save 4ML/Day of hot water for a capital cost of £3.9M. This would reduce carbon emissions by 13 tCO2e and energy by 64,000 MWh/year.
A campaign to target the largest component of household water use (the toilet) has great water reduction potential. WC refurbishments and retrofits on Scotland's WC stock would cost £82M and reduce water demand by 112ML/day (13% of total water demand). In eight megazones, the program for replacing old 13L WCs would be cost effective with an 8.5 year payback period.