Working with the Cleveland Water Company is an adventure, here are a couple stories. There does not seem to be much rhyme or reason.
1) We had a bill around $8,000. We argued that we could not find a leak. 2 months later we received an adjusted bill where the high usage mysteriously dissappeared.
2) Another bill was around $9,000. Water Co would not back down, we had to do a monthly payment plan for $x per month to get it paid off
3) Currently, we are working on another issue. There was constant usage early December that stopped on its own, plumber could not find a leak. Starting on 1/1/22 it started again. We are having the toilet flappers changed as a precaution as that is one thing that could cause intermittent usage but not the $11,000 level you are experiencing.
You can go to clevelandwater.com and create an account. You will find an hour by hour usage report which will help you to isolate when the water department claims the usage was made and how much. If you PM me, I can send an example report from our current issue (can't seem to attach to the post).
Unfortunately, I do not believe CMHA will pay for this, they pay up to their expected reasonable cost of the utility and that is all. Keep arguing with the water co, maybe you will get lucky and the balance will magically go away.