Probably you think it's important to study poverty. The census is used to study poverty and to study differentials in poverty between racialized groups. It's used to study poverty of first nations people.
It turns out that one of the reasons people are poor is because their housing is expensive. So one of the reasonable things to do in the census is to ask people about their income and the cost of their housing.
One of the problems with the cost of their housing is that you can't ask a single question and measure it accurately. You need a series of questions, and that's the reason.
So the reason that the question about water is in there is because it's an element of housing cost, housing cost is an important element of poverty, and we use the census to study poverty because it's an important aspect of—