Suspiciously High Water Bill - MJ in CO?

[Brian Kraft]

Howdy. I've got a young guy renting a house of mine in the city of Denver/Unincorporated Adams County. He pays the water bill, but I have it set up through Denver Water to receive  copy of the bill, just so I can keep an eye on the bills. Last month, all of a sudden the bill which is generally in the $10 to $30 range, jumped up to $60 (which he paid). I was curious about the increase though. Now the latest bill arrives and the current charges are $240. WHAT!?!? For water. For a month. Now, either there's a crazy leak that I'm/he's unaware of or all that water is being used for something very specific--like a crap-ton of plants.

If he's got some big marijuana operation going, my big concern is fire (well, and apparently water) damage concerns. Not to mention, the lease specifically prohibits growing of marijuana on the premises. I have not entered the property since he's moved in a few months ago, so I have don't know for sure what's going on.

So, what would your approach be?