Every state has a standard lease that realtors use.

It could be this was a standard periodic reassessment to account for market value increases and there's nothing to fight.

Roof is approx 15 yo. 4 water heaters been replaced in past 5 years. current brings in $5200 month.

Ask yourself what makes your property worth $2100 (incl water) when rents in the area range from $1500-1800 (assuming that doesn't include water)? 

Where is the water flowing when it rains?

Quote from @Kerry Noble Jr: Preforeclosures are best called or door knocked.Tax delinquent or code voiolationsPreforeclosures, Tax delinquent, code voiolations, probates/inheretence, quit claim deeds, water shut off are the best lists.Understand it is a volume game. sending out 500 mailers probably won't yield any results.

Inflation, cost of utilities (water/sewer), maintenance, and market rental rates.

What is the industry standard for underwriting?

He installs our water heaters for $260 + the tank.

We have been applying our standard question sets but feel we can do better.