Benjamin,The Umbrella policy generally just provides additional limit of Liability if the underlying limit of the Homeowners, Dwelling Fire, Auto, boat, etc. is exhausted in a claim.Most of our carriers that offer Water & Sewer line coverage offer it as an endorsement on the Homeowners or Dwelling Fire (for 1-4 family rental dwellings) policy. 

Even if the two properties are in the same town, the quotes could differ from different carriers due to age, fire protection, value, etc.

Most times the companies that have the best options for singles will not have the best options for buildings with 4 or more units.Many of my investors who have a portfolio with different property types will have more than 1 insurance carrier to get them the best coverage and pricing.

I have one Insurance carrier that will allow up to 10% Knob & Tube. 

Bad workmanship is not a covered loss by the insurance carriers.

Ask the broker which carriers (markets) they shop.

We have 20+ local garbage carriers and you can contract whomever you want.

We inherited a tenant with a breed prohibited by our preferred carrier.  

Also, was it difficult to find a carrier?

So I tapped into my existing network of lead generators; my landscaper, pool guy, UPS driver, Schwan’s food delivery driver and mail carrier.