Two things.

Firstly, would it make sense to have a “water-cap” and if you hit it your house can’t get water for the rest of the month?

Secondly, everyone’s cap resets at the same time. Meaning that everyone has full access and aren’t at their cap. How does that prevent saturation up to the point that [speed]*[time]=[cap] for the heavy users? Because it will be days until a reasonable cap is reached.