Parents keep getting minimum water bills.

Hey y’all, I don’t want to jinx anything but my parents live in cypress and have been getting a water bill every month but it shows zero usage and only charges the minimum of 30$ to their auto pay, and this has been happening for about a year and a half. No one’s going to say anything if this is just a case of falling through the cracks, but I’m worried that this might bite them in the ass years down the road. Has anyone had this happen?