In 1927, when the works of the construction of the Marathon Dam began, the water was distributed in Athens every fourth day and was available for about one or two hours. In 1928, 15% of the consumers were supplied with water every day, 75% every other day and 10% of consumers living in remote areas, such as Pagrati, every four. In 1927 and 1928, Ulen & Company installed water meters in the distribution network in order to charge according to the consumption and not to a flat rate, as used to do until then. This change resulted in a significant decrease in the average consumption which meant that, while the Marathon dam construction was in progress, there was more available water and many areas could be supplied with it easier. At the same time, work started in order for Piraeus to be supplied with high-quality water directly from the Marathon dam. Until then, Piraeus was supplied with low-quality brackish water from wells located in the ​​Agios Ioannis Rentis area.