4 - Plex Water Spigot - SECURITY

[Jason James]

Hello all I have a 4 - Plex that has an outside water spigot and I "think" others in the area "other buildings" and or my tenants are using this spigot when they aren't authorized to. It has no handle and has a stem that I have a key for but you can easily use pliers to turn it on. This could potentially run the bill WAY up and since I pay water I want to lock this thing down. 

What are you guys doing in this situation? Ideas? 

Thanks