Maryland Code, Tax-Property § 14-849.1

(a) In Baltimore City, the Mayor and City Council may not sell a property to enforce a lien for unpaid charges for water and sewer service unless:

(b) Notwithstanding subsection (a) of this section, the Mayor and City Council may enforce a lien on a property other than residential property or real property that is exempt from taxation under § 7-204(1) or (2) of this article for unpaid water and sewer service that is less than $350 if the property is being sold to enforce another lien.

(c) This section does not affect any other right or remedy of Baltimore City for the collection of a water and sewer service charge.