Think of it this way; 70% of the planet is water. Of that water only 2.5% is fresh water, 68% of that is held in glaciers. About 1% of the fresh water on earth is liquid.

That 1% is the absolute maximum quantity of what’s used for drinking, and the steps between ground/reservoir water and the tap in your home involve MASSIVE quantities of electricity and effort to make it so it won’t kill you.

What you’re suggesting doing is turning the tap on and sending that fresh drinkable water right back into the sewer to generate a miniscule amount of power, since the average tap pressure at 1 bar means you’ll be making sub 100W of power, hardly enough to power the big light in your kitchen if it’s got more than two incandescent bulbs or spotlights, let alone a kettle or a microwave.