Urban Residential Water Demand and Household Size: A Robust Meta-Regression Analysis*

We present the results of a meta-analysis of household-size water demand elasticity. The analysis is based on 75 primary studies. As there is evidence of publication bias, publication bias–corrected estimates are reported. For indoor water use, we find that in countries with gross domestic product (GDP) per capita below $10,000, the household-size elasticity is approximately 0.4–0.5, and in countries with GDP per capita above $10,000, it is approximately 0.5–0.6. For outdoor water use, we find that there is no increase in water use as household size increases, at low incomes (GDP less than $5000 per capita), but the effect becomes positive at higher incomes. In countries with a GDP per capita between $5000 and $15,000, the household-size outdoor wateruse elasticity is approximately 0.1, and in countries with a GDP per capita above $15,000, it is approximately 0.2. The positive household-size elasticity implies that the cost of meeting basic water needs, per person, increases with household size in countries that use increasing block pricing for water. The use of a single volumetric price, equal to marginal cost, combined with a fixed charge, would lessen this effect and also improve system efficiency.