The growing need to integrate in the electricity grids highly variable and not easily predictable renewables, such as wind and solar, poses serious problems to grid operators for load balancing, and in particular it requires the availability of an increasing share of particularly flexible generation reserves to cope with intermittency of wind and solar generation. Moreover, considering that the daily evolution of energy production from conventional plants is generally out of phase with respect to the energy demand, it is extremely important to have energy storage systems able to manage the difficult relationship between availability and demand in order to stabilize the frequency of the grid and ensure continuity of service, thus avoiding the risk of black-outs. The pumped storage hydropower have the advantage of being able to perform this function more efficiently than other storage systems (eg, CAES, batteries, flywheels, etc.). Pumped storage plants are equipped with reversible turbines for moving water between two reservoirs placed at different elevations. During “off-peak” periods they use the cheap energy provided by the network to pump water from the bottom to the top reservoir. During “peak” periods, water is then released to the bottom reservoir through the turbines to generate power, which can be placed on the market at higher prices. Although many of such plants are already in Italy, which boasts a long tradition in this field, in light of the ongoing climate changes and the constant rising of fossil fuels costs, it is necessary to reevaluate the use of this important resource through the upgrading of the existing facilities and by identifying optimal sites for new reservoirs. In this paper the results of a research aimed at evaluating, with the support of a geographical information analysis tool (GIS), the additional storage capacity achievable in Italy, both through the construction of new reservoirs and the rehabilitation and full utilization of existing ones, including those for irrigation, drinking water, industrial and lamination purposes. Moreover, according to the latest developments and successful experimentations of sea water pumping systems, which have the obvious advantage of exploiting a nearly infinite resource and do not require the construction of a bottom reservoir, potential sites along the Italian shoreline have been identified as well. The investigation showed that the residual potential for the construction of new hydro pumping plants, both conventional and sea water, is relevant and if properly exploited could facilitate the integration into the Italian grid of large amounts of renewable energy.