Water quantities for public and private use in Pompeii

Abstract

The water-supply system in Pompeii delivered water to both public and private water users. Aqueduct water was distributed in three main water pipelines. The aqueduct water was led up to fill lead containers on top of a number of water towers, and from there it continued downhill from one tower to the next located at a lower level. All top containers also had connections to small individual lead water pipes to public and private users in the different districts of the city. However, it still remains unclear how and with what efficiency aqueduct water could reach all users, some of them at a far distance from the water towers, in a system based on gravity flow. In this study the focus is to explain the water flow in the small water pipes from the top containers to public and private users. The study presents a calculation method based on Bernoulli’s equation for fluid mechanics. The simplified form of the equation is the result of an adaption to Pompeii’s conditions and has been used for the calculation of water velocity and the water quantity in water pipes when three geometrical variables are known, the head, the length of the pipe and the diameter of the pipe. The calculations of the water quantities in small water pipes have shown that less than half of the total incoming water quantity to the city was supplied for public use in the street fountains and the public baths, and that at least half was supplied for private use. This means that the water supply for some private users must have been considered from the beginning. The calculation method has only resulted in estimations, but the equation presented is exact and deserves to be used in the future as more exact values of the three geometrical variables are measured.