Here's the easier fix...
Require any water barrel inside of a house to be a secured barrel that was then filled by someone with access to it. It then functions as a water trough, but with only the charges as the water placed inside. It cannot be moved through.
All barrels set down outside a house do not have such requirements, but CAN be Axed by anyone, and allow move-through.
This allows use of water barrels by a house owner for RP and personal uses, while allowing external uses subject to the whims of passers-by. At the same time, it would remove the use of water barrels inside homes as an IDOC strategy.