However, just before the tenant moved into the property our PM discovered the brand new water heater we just installed had been stolen (there is outside access to the utility room and even though there is a metal security door they had ripped it off).

Here's a list of what we ask for in our LOIs and contracts:Operating financial statements for the property, including income statements, expense statements, capital expenditures, for the last two years of operation and year-to-date financial statements for 2020.Prior two (2) years tax returns and addendums for the Property.Current tenant leases, tenant correspondence, tenant credit information, tenant security deposit register, and delinquency report.Onsite staff payroll records to include salary, bonuses, payroll taxes, benefits, etc.Monthly owner statements and rent rolls for the past 12 months.Contracts, service agreements, and files pertaining to the property.List of maintenance all maintenance requests (complete and incomplete) for the last two years of operations.Real estate tax billings and assessments and other correspondence pertaining to real estate tax calculations at the property.Copy of Insurance Policy and claims documentation (loss runs).List of capital improvements and any and all necessary related documentation and warranties.All existing warranties and guarantees from architects, contractors, and material and equipment suppliers, all of which would be assigned to Purchase.Any existing environmental Phase I/II reports, engineering reports, soil, mold, radon, asbestos, hazardous substance, termite, or other tests, studies, or reports.Any existing appraisals.Itemized inventory of all personal property.Twelve (12) months of utility, water and sewer bills.Twelve (12) months of bank statements.Verification of additional income from operations including but not limited to application, pet, late, and other fees, etc.Copies of title policies, title reports, land surveys, site plans, deeds, or any architectural plans for the property.History of or pending litigation against the Property, its owners, or its managers related to the Property or the operation thereof.Such additional information, documentation, or access as Purchaser shall require

I live in an older city, so it is not uncommon for landlords to be responsible for heat and water (read gas bill and water bill). 

Most insurance policies don't cover flood insurance and its a common misconception that water damage is flood coverage and it is not.

I am asking cuz, even if the house needs tons of work, still have permit, water, septic system, electric is in place.

You're completely forgetting to account for taxes, insurance, vacancy, CapEx, Repairs, management, water/sewer, lawn care, snow removal, professional/admin fees.

Water Heater (over life-expectancy)3.

If you triple the value, you should expect the taxes to triple as well.What about water/sewer, shared electric or other utilities, lawn care/snow removal (if applicable), trash pick up, admin and professional fees?

If not then need to budget for floors 10 year life span, appliances and hot water heater 12 year life span, hvac 20 year life span, bath and kitchen remodel 20 year life spa, etc.

Look for updating furnace and/or hot water heater.