I read my water meter every week and I record the reading on a spread sheet to track it. I record it by date and time. If I happen to notice the city water meter reader reading my water meter, I immediately go out and read the water meter after him and record it on my spread sheet. I also record on the spread sheet that the city water meter reader read my water meter, date and time. My spread sheet breaks it down, to how many gallons of water my household consumes daily.
Immediately after I noticed the error on my statement, I went out to read the meter and photographed the reading on the water meter. I emailed my photograph of the current meter read, and my spread sheet to the city staff.
The city staff came out and re-read the meter. They called me, informed me that they have rolled back the recorded reading on my statement and revised my statement to credit it 17.48. Rolled back the meter reading from 497 units to 487 units.
The city staff reading water meters obviously can have errors when they are recording the number of units on your water meter. It may save a few dollars, as in my case 17.48 if you track your household consumption. Of course, when the meter reader comes around the next time, he would be in a state of confusion trying to record reverse number of units consumed.