Medieval Warsaw, which was located on a rise, was supplied with water mainly from the many nearby steams, naturally flowing towards the Vistula, and by numerous sources and wells. The little streams on the rise, supplied in large measure by rainfall, were not hydrologically stable. In time, a system was built with water retention reservoirs called nalewki.
The next stage in the history of Warsaw’s water supply, at the beginning of the 16th century, was the bringing of water from the nalewki directly into the Old and New towns by means of a system of wooden pipes, into which the water was manually pumped. In the middle of the 18th century, at the initiative of the then mayor of Warsaw, Dulfus, pumps were placed on the receiving pit. This was the first municipal water mains.
However, the growing city needed much more water and, in addition, the sources and streams started to dry up.