If he is truly deranged or mentally unstable (possible with neat/bacteria-free issues)....you may be able to send a contractor (or multiple contractors) over to the crawlspace and leave some unpleasant smells, take pictures, and look for indications of illegal drugs.

Add bacteria every quarter. 

According to its site: The Host Protection Insurance program does not apply to liability arising from (1) Intentional Acts including: (i) Assault and Battery or (ii) Sexual Abuse or Molestation - (by the host or any other insured party), (2) Loss of Earnings, (3) Personal and Advertising Injury, (4) Fungi or Bacteria, (5) Chinese Drywall, (6) Communicable Diseases (7) Acts of Terrorism, (8) Product Liability, (9) Pollution and (10) Asbestos, Lead or Silica. 

I'm unfamiliar with building codes in Chicago but in Massachusetts where I do HVAC work we cannot allow the tank to be less than 120 degrees as below that temperature bacteria can grow in the tank.

.* Bacteria and Virus - This exclusion especially came to lite as we hit the COVID pandemic. 

Mixing treated water with fresh can create too much bacteria growth and cause system falure.