Boston landlords estimating expenses

[David Shapira]

Hi everyone, I'm a first-time investor looking to purchase a two/three family house in the greater Boston area. I'm hoping for some guidance from local landlords on estimating expenses. 

Aside from PITI/PMI, I'm estimating 5% of rental income for vacancy, 10% for maintenance/capex, and 10% for property management. Are these numbers fair? What should I budget for water/sewer? What other expenses should I plan for?