Or simply have them turn the valve located on the wall clock-wise until closed to prevent excessive water usage. 

You have to track that usage, and their is admin involved in that so that would be a negative for most landlords.

I see your worst case as being a "no", I wouldn't let the rent hike idea stop you from asking for a reasonable concession- especially if your utility company can tell you your usage is high compared to similar units. 

He sends inappropriate text messages (pictures on mens genitals) among other things calling me bad words and what not.

What will my kilowatt usage look like if it’s running day and night?

Tell them that the two of them are responsible for ensuring proper usage of the appliances including the garbage disposal. 

We told them we would cover 45% of the electricity from this past month, as that was what we estimated their usage for cooling was on their unit. 

I’ve been having damaged from improperly installed units and also if there’s not hookups it’s usually because the building is on a septic system and I don’t want that much water usage through the system.

The front 1/3 will be dedicated to office/commercial use and the back 2/3 will be living space, but the usage is flexible throughout.  

Examples: don't adhere to max number guests, rent to inappropriate guests (handicapped person in a walk up was my most memorable!)