How Roman engineers selected their water supplies

An account of a historical Roman water supply system in Zonguldak, northwest Turkey on the Black Sea coast is presented. This ancient water supply system demonstrates Roman engineering expertise in water management and hydraulic engineering applications. Although there is a river located near the Roman city (Filyos) with an average annual discharge of 89 m³/s (1970-2005 data), Roman engineers preferred to provide water from a 15 km distant karstic spring. The region, unlike the Mediterranean region, has good rainfall (1100 mm), which indicates another water quality criterion for selecting the karst spring as a water source. The most important factor in the Roman choice appears to be water temperature. This selection criterion closely agrees with suggestions on water quality issues made by the Roman architect Vitruvius.