Maybe this could be applied to water towers? That's a lot of potential energy just sitting there.
Hydro power storage is fantastic but needs truly ridiculous amounts of water and height deltas to make sense.
A kitchen tap provides like what, 0.2 liters per second?
3.8Mg * G * 50m ~ 1700M Joules which is about 500kWh.
I got 450 kWh? Maybe you meant 1/2 MWh
Energy is force times distance. You need to know more than just pressure to calculate energy.
(A bicycle tire at 120psi has a lot less energy than a truck tire at 90psi.)
there isn't much energy in a water tower. and that water is already doing work, pressurizing the water system.
And you have to maintain water in the tower in order to keep the water distribution system pressurized.