Double that contingency budget!

Make sure you run your numbers both ways.Include a budget for initial repairs.

criteria/budget/return expected/hold time, etc

The rehab budget got blown completely out of the water by "surprises" but that's half of the fun of any good learning experience, isn't it?

Does your pro-forma include a development budget with all soft and hard costs included as well as an operating budget, equity cash-flows, sources and uses of funds, lease-up time table, sales proceeds analysis, etc.? 

If you don't own the 20 units yet you can either budget for the CAPEX or you can speak with your lender about doing a LTC where your rehab money with be incorporated into the loan.

Trucking in bottled water for the tenants on a daily basis is also very expensive.

I am planning to buy a fourplex property as investmestment property, my budget is 200k downpayment.Any recommendation as to where i should buy the rental property?

Hang out in the parking lot of Home Depot/Lowes and write down phone numbers seen on the contractors trucks. 

A capex budget needs to include but not limited to: roof 25 year life span, 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 span.