Roommate hooking chain over inflow

[Kimberly Brinkmeier]

I have a good roommate that pays on time and just does his own thing.. however a few weeks after he moved in (mid-Feb) I heard his toilet (main toilet) running and found he had hooked it a few links higher so the flap wouldn't seal. I fixed it and all was fine. I had had a plumber replace the toilet insides at the end of January and the toilet was flushing perfectly, so not sure why he wanted to play plumber.

This is three months later and on a Tuesday I hear it running again and he had the chain hooked around the inflow clip I unhook it and notify him. His response was he did not touch the inside of the toilet and it must have hooked on a normal flush. I think weird and move on. Friday night he had it hooked again. It was near midnight so I turn the water off so I can talk to him in the morning. In the morning the chain is unhooked and at the very end of the chain, so I turn the water back on. 

I try flushing the toilet to try to get the chain to hook on the inflow, but the chain is only bouncing up.. it would need to go 3 inches over to the side and up to be hooked. So this hooking of the chain is an intentional act. 

I have a well and septic and replaced my drainfield last year in February. Two questions.. first, what would the appropriate reaction be to him purposefully making the toilet continue to run.. and second, is there any way to track the water that runs through a toilet? (He works a half mile from the house and is home before me. My job is 45 min driving away so if he has the water running it could run for 10-12 hours without me being in the house to fix it).

Thanks in advance for your help!