because a water tower is built to a certain height needed to maintain pressure if you impede flow you then need to add height and that requires more energy to pump.

The only way to make electricity from flowing water is when gravity causes the flow.  There are a few places that pump water up at night for peak generation the next day but its not free energy and you loose around 40% of the energy to the pumps, motors, turbines and generators.

If you put it in a tile it would need to be in a area where you have a fair amount of slope as you will back water up.

Looks to me as a great way to spend money and accomplish very little.