How do I report a sewer assessment on my rental property

This, from IRS' Publication 527, Residential Rental Property:

Local benefits generally increase the value of your property, such as charges for putting in streets, sidewalks, or water and sewer systems.

The best place to put it would most likely be in the Real Estate Tax section in Rental Expenses (see below screenshot).

To do that:

1.  Click Federal on the left-hand side menu.

2.  Click Income & Expenses across the top.

3.  Scroll down to Rentals, Royalties, and Farm and click Show more.

4.  Click Start or Revisit by Rental Properties and Royalties (Sch E).