For their study, published in the January 2021 issue of the journal “Water”, water experts from ISOE examined daily and hourly water consumption volumes during the first wave of the Corona pandemic. The aim was to analyze the effect of the lockdown measures on water consumption in a scientifically sound manner and to make it visible in distinction to other influences. For this purpose, the scientists evaluated data from the almost one thousand square kilometer supply area of the water association WBV Harburg. In this area on the edge of the Hamburg metropolitan region south of the Elbe River, more than 180,000 people are supplied with drinking water.
In order to capture the effect of socioeconomic and sociocultural restrictions on water consumption during the first wave of the pandemic, the scientists cleared the consumption figures from other effects. Increased water consumption due to heat was for example removed using a linear mixed model. “Compared with water consumption figures from previous years in the suburban study region near Hamburg, there was an increase of 14.3 percent for 2020. We attribute this increase to changes in daily routines during the lockdown,” says Deike Lüdtke, lead author of the study “Increase in Daily Household Water Demand during the First Wave of the Covid-19 Pandemic in Germany”. Changes in leisure activities – such as bathing in private pools or an intensified gardening – can also be assumed as causes for increased water consumption.
Understanding daily routines to ensure supply security
The changed routines during the first wave of the Corona pandemic were most noticeable in the morning and evening. “Changes in daily consumption are not trivial for water utilities,” Lüdtke says. Water companies rely on accurate forecasts, she says. “Sudden changes in consumer behavior can jeopardize the supply security of water companies. Therefore, it is crucial that everyday consumer routines are better understood and taken into account in water demand forecasts.”
ISOE scientists anticipate that certain demand patterns attributable to behavioral changes during the initial lockdown will remain relevant for future water demand forecasts. “Demand patterns throughout the day showing a temporal shift regarding the usual peak demand in the morning and higher consumption in the evening, suggest new everyday practices, for example in connection with mobile working, that could be maintained beyond the pandemic,” Lüdtke said. Water suppliers should therefore prepare for adjustments to altered water use with the help of demand forecasts that should be as accurate as possible – although adjustments to future water consumption will also be necessary due to changing usage patterns during the mid-summer droughts.
Water demand forecasts are increasingly difficult to make
“Realistic planning of future water consumption is becoming increasingly difficult because many influences on the demand have to be taken into account,” says co-author Stefan Liehr. In addition to climatic conditions, he says, demographic developments are also decisive, as are economic structures, which change particularly in times of crisis. This always leads to spatial shifts in demand, for example from commercial areas to residential areas. In order to make precise predictions, it is also essential to examine the habits of different user groups.
The current ISOE study in the above mentioned supply area confirms that: “The better we empirically study the everyday behavior of different user groups, the better we can predict what kind of consequences changes in everyday routines may have for supply security,” says Liehr. As head of the research unit “Water Supply and Land Use” at ISOE Stefan Liehr has already helped develop several forecasting models regarding water demand that can reliably map the complex influences in a supply area on a small scale.
Lüdtke, Deike U./Robert Lütkemeier/Michael Schneemann/Stefan Liehr (2021): Increase in Daily Household Water Demand during the First Wave of the Covid-19 Pandemic in Germany. Water 13 (3), 260