tankless heaters last longer as they aren't holding 40 gallons water.

How many gallons a month are they using?  

We paid about 5k to replaster and retile the waterline of a 25000 gallon pool...blueish quartz plaster mix last year.

The best I can seem to find is 30 gallon for $300.

Did they stress out over not having enough by spending an extra few minutes to depower the entire home before leaving or drive an extra ten minutes to save $0.08 per gallon of gas?

After research and two visits to house (in Sayville, NY) there is interesting situation developing: this property is in very good condition, and need only some paint and few gallons of clorox, utilities are off, comparable houses in area were sold for #380-420k. 

Total water usage was close to 69,000 gallons for September.  

If I was guess I would say minimum of 100k to buy the equipment .. then you have staff and that is always an issue.she also has an ATM  but that has caused her to get broken into a few times.. but it does create revenue.and its a lot of work.. she also serves light food  breakfast sandwiches  lunch  sandwiches etc. you need commercial coolers in the back to store the gallons upon gallons of milk etc.I have seen out our way these do pretty good and that's the little mini drive through stands that are manned by one person and or two max.. all in a little trailer with drive lanes on both sides.. hitting the commuter traffic. you get permission to put one in a shopping center parking lot that kind of thing.  

I am a contractor , I dont supply a count of 2x4's and prices , tubes of caulk and gallons of paint .  

They could be "Copy of drivers license" or they could be "Borrower to provide 4 gallons of milk from a virgin goat".