There were many vulnerable households in need.
In a state of backward agriculture and natural economy it will sometimes be more profitable for the conquerors as well as for the conquered to leave the dependent population in their own households and on their own plots, at the same time taxing them heavily in the way of tribute and services.
Some households are more likely than others to benefit from switching from a flat rate to a metered water billing.
It is particularly useful in households who have several flameless candles as switching these on and off several times a day can be time-consuming.
But as households vary, so do their routines and their chores.