Tanks have always played a crucial role in urban water distribution systems. With well known advantages (as to guarantee
reserves for emergencies) they are widely used. But they present, as well, inconveniences such as their contribution to a higher
water age and are, as will be seen, energy-hungry. This paper introduces an indicator to assess energy savings of direct water
supply (without head tanks) with regard to the traditional indirect one (throughout head tanks). Furthermore a case study is
presented showing the reliability of this indicator. The paper concludes with an economic comparison of both strategies.