Connecting single hot water tank to individual electric meter

[Rich Gabrio]

I have a small 1000 sf retail duplex.  The building can accommodate a single tenant for the entire building, or individual tenants for two units.  Currently, I have two tenants occupying the building, and both units are served by a single gas hot water tank which is located in a common area which only serves a hot water faucet in each unit.  Electrical service is individually metered (two meters), water and gas both have one meter for the entire building, and my tenants pay based on percentage of square feet.  One unit has electrical heating, the other has gas. In the case of gas billing, one tenant has the gas service in their name (the unit with gas heating), and the other tenant reimburses for their consumption (which is exclusively hot water consumption).  The tenant with gas heating would like to suspend gas service, and use space heaters to save the cost however, I do not want to drain the tank, and have it sit idle over the winter if she were to do this.

I would like to, if there is a relatively cost effective way, convert or replace the existing hot water tank to an electric tank, and therefore have the hot water energy consumption routed to each tenant's electrical meter. Is this possible without introducing an additional water source to the building?

I do not plan on holding the building long term therefore I have no desire to  move to multiple gas and water meters.  

Thanks for any information.