Splitting utilities on a singly family home with basement suite

[Shawn Hochhausen]

Hey everyone,  I am in the process of building a suited single family home as a rental property and am stumped on the best way to split utilities.  My biggest issue is how to split the electric bill on the water heater, does anybody know of a way to sub meter a hot water tank?  Any knowledge or recommendations on sub metering is greatly appreciated!