Is the original water pressure produced by water towers or electric pumps? In the case of the latter, this is seems to me to be a classic case of conservation of energy.

Like putting a windmill on an airplane, all the turbine is doing is feeding off an existing powersource. Sure, if the private water companies (booooo!) are producing excess PSI, then this might act as a small-scale method for re-capturing energy. However, a better way of saving energy would be to optimize pressure output from the source and install pipes that equally distribute the minimum promised pressure.

Tell me if I’m wrong! Just running off high school physics, so it’s likely.