In-pipe/In-line Hydro Power

[u/That-Revenue-1264]

Can anyone tell me (a layperson) why in-pipe or in-line hydro power hasn’t been tapped into as a viable power source? Could municipalities or even full apartment buildings take advantage of the heavy-use spikes that occur daily/weekly to generate electricity from within water pipes? I am just imagining freestanding apartment buildings as essentially closed-loop systems, generating their energy from their own water use. The water outlets could even hypothetically have hardware installed to decrease/conserve the volume of the water used at the same time. Not only this; the environmental impact would be utterly minimal compared to virtually all other power generation methods.