Question about tax treatment of Sewer Lateral Compliance fees

[K Khanna]

We had to get the Sewer Lateral Compliance Certificate before close of escrow when we purchased our rental property last July. This certificate is good for 7 years. 

How do you normally take a deduction for this expense? We were charged $3100 by the plumber who did it and obtained the paperwork from the City. 

Do you write it off completely as expense in the first year? OR

Do you amortize it over 7 years? OR

Do you add it to the basis of the property?

Any helpful responses appreciated as we have barely 1 day more to file the taxes for 2016! Thank you.