City Burdening Our Expenses (Streets/Water/Sewer)

I’ve been using the 30-40% of revenue for expenses rule based on who pays W/S/T, tenants or park.

I was looking to revise those estimates in cases when:

Park has city owned streets. (I realize weather could change this but on average)

Park has city owned water and/or sewer infrastructure and the city bills tenants directly.

How much cost is the city taking on in these instances that we can reduce from our 30-40% estimate rule?

Looking for a guide from those with more experience.

Daniel Simms