On top of that, a drunk driver plowed into a separate apartment, taking out the gas meter with it, one day before a tenant move-in.

I know they are zoned SFH with just one meters (not grandfathered in with multiple buildings on same lot).My question is.

Units all on one water meter.

It also has 2 meters but isn't zoned as a duplex.

It is not separately metered and right now I don't see adding a meter as an option (cost/not zoned for MF). 

Sellers removed UST (cost was $20k for them), already 3 gas meters and installing two other boilers to separate heat.

We just bought a duplex, which has separate meters for electricity. 

Another has had the electrical wires in the house 'recycled' to the extent that the electrical meter and main connection wire was removed to prevent a fire if turned on by accident or bypassed by the squatters. 

Oh and the electric company has it figured out with solar if you net meter you don't get Kwh you get dollars. 

To maximize cash flow, consider setting up smart meters to track energy usage and possibly offer incentives for tenants who save on energy.