Drought events have the potential to constrain the normal supply of water to water company customers, as well as affecting the environment and other water users. In order to maintain essential supplies during droughts, water companies communicate with their customers and have the potential to limit certain types of water use. It is important to evaluate the impact of these drought demand management measures, to improve how they are managed and deployed.
The objective of this study was to quantify the change in water use due to the implementation of drought measures during 2022 including the communication campaigns delivered by all companies and the Temporary Use Bans introduced by six water companies in August 2022.
Weather in 2022 was extreme, with more severe heatwaves of a shorter duration than experienced in 2018, which was the most recent preceding dry year. Weather analysis suggests that the increased campaigns in 2022, and the need for Temporary Use Bans was due to the drier winter and spring in 2022, compared to 2018. This was combined with the prolonging of hot and dry conditions into September 2022. In contrast, the hot dry weather in 2018 generally broke in August that year.
The implementation of Temporary Use Bans was observed to reduce distribution input consistently in all six company areas where these interventions were applied by 3.34% with a standard deviation of 2.78%, while household demand was reduced by 6.62% with a standard deviation of 1.17%.
As expected, the effect on household demand is stronger and less uncertain, while the effect on distribution input is diluted by non-household consumption and leakage, and therefore is lower, but still significant.
The quantitative impact of communication campaigns is more difficult to determine: they are more subtle and less binary nature than Temporary Use Bans and there is no standard scope or process for the water companies to collate information on communication campaigns. However, the modelling conducted does show a reduction in distribution input prior to the implementation of Temporary Use Bans, both in companies that implemented restrictions and in the ones that did not.