75 gallon HWH, is it enough for 9 units?

[Kathy Henley]

I am looking at a mixed-use building and the hot water system looks squirley. 9 residential units and 2 retail store fronts share one commercial hot water heat of 75 gallons.  Landlord pays the hot water expense and, the theory is, the rents cover it.  This is not true, as the rents are below market.  I like an undermanaged building, if I buy it according to the actuals. But one must anticipate the cost of improvements. Is a shared water heater workable?  One bedroom/one bath untis. Thanks