A GIS-Based and Statistical Approach to Estimate per Capita Water Consumption Based on Different Residential Building Types

To design sustainable water supply systems, utilities need to determine the average per capita water consumption along with factors that influence it. However, data on residents per building are often unavailable. This study introduces a GIS-based approach to estimate residents per building despite incomplete data. Building height and size were determined and spatially linked to water consumption data. These values were used to calculate the living space and the number of residents per building. A comparison with actual residents from Study Site 1 showed high agreement (correlation of 0.7), confirming the method’s reliability. With an accuracy of ±1 person, 66% of single-family homes and 17% of apartment buildings were correctly estimated. The analysis further showed that single-family home residents consume about 130 L per day, while those in apartment buildings use 105–114 L per day. The presence of swimming pools was identified as a significant factor. A resident in a single-family home with a pool consumes around 153 L per day, while one without a pool uses around 126 L per day. This approach provides a method to estimate per capita water consumption, enabling water utilities to plan sustainably, even in regions with limited register data.