Determinants of residential water demand in Germany

We econometrically analyze the impact of several economic, environmental and social determinants for the per capita demand for water in about 600 water supply areas in Germany. Besides prices, income and household size, we consider the effects of population age, the share of wells, housing patterns, precipitation and temperature. We also explore why current per capita residential water consumption in the new federal states is about 30% lower than in the old federal states. Since average cost pricing may cause an endogeneity problem, we apply instrumental-variable procedures in addition to single equation ordinary least squares, but find no evidence that prices are endogenous. Our estimation results suggest that the price elasticity of water demand in Germany is around − 0.24. The income elasticity is positive, decreases with higher income levels and is at least three times higher in the new federal states than in the old federal states. Current differences in prices and income levels explain about one third of the gap in residential water use between the two regions. Household size and the share of wells have a negative impact on per capita water demand, and water use increases with age. Finally, the findings provide some evidence that rainfall patterns rather than total rainfall affect water consumption, while temperature appears to have no impact at all. All outcomes are robust to a log-log and two types of semi-log specifications for the water demand function.