Long term visitors raise water bill

[Jose Quinones]

Bottom line up front: how much time is too much time for visitors? 25%-50% of the month? 75%?? 

My water bills are high…I think it’s because my tenants have their bf/gf there all the time. Not “living” but stay there a lot. 

I’d like to send a notification addressing this to my tenants. Any suggestions on how to word it? I’m gonna add a clause to the leases too but again, how much time? What should it say?

Don’t want it to sound like a threat of some “finger wagging” or “slap on the wrist”