The restoration of the Roman water supply system in 1880 for the water supply to Split

The paper describes the development of the Urban Water Supply System (UWSS) for Split (Croatia) in the second half of the 19th century. The selected concept of the water supply system was entirely based on the system of Emperor Diocletian's Palace from 305 AD, which has not been in operation since the 7th century. The research is based on the analysis of historical data and the actual state of the water supply system of Split. The study provides a clearer insight into the process of choosing the optimum concept of water supply system, the operational characteristics of Diocletian's system and the restored UWSS. The sustainability of both the Roman UWSS and the 1880 system, which has a significant part of the aqueduct still in use today, have been confirmed. It is an example of a zero-carbon water supply system running entirely on renewable energy: gravity.