I rent an apartment in a small building in Detroit, MI. There is one other tenant in the building and an office space. My utilities are included in my monthly rent. The building owner recently removed the old gas water heater and replaced it with an electric one. The old water heater was approximately 80 gallons. This new one is only 20 gallons which runs out of hot water in less than one persons shower. I would like to know if there are minimum requirements for water heater sizes in rental properties in the Detroit, MI area.

This type of thing is usually governed by municipal law. Contact your town's Board of Health to find out if there are any specific laws about it.