It's a common enough thing in many urban areas to have high sewer fees. They make it look like you are paying for measured use out, but in reality, it is part of the water use bill. They could just list it under incoming water use, but they divide the bill to make a point.
It is aimed at making you think about wasting water.
I've been trained - I have caught myself running taps more now that my water isn't metered. I have stopped that. I am surrounded by fresh clean water, but it does have to be treated if it's going to stay that way, and fees are reasonable ways of making people think.
If I lived I lived in one of the vast spaces where agriculture and industry have polluted the aquifers, it would be more important.
It seems a bit silly to ask for someone's water bill when it's so easy to look up how these things are done online.