53 Pa. Stat. § 16557
The said mayor or recorder, and four aldermen, together with any four of the regulators of the said city, for the time being, shall appoint and direct the regulation of the said streets, lanes and alleys, and common sewers, with the degree of descent of each water course: Provided always, That no common sewer or water course, to be laid out, shall be so regulated and laid out, as to run through any lot or ground belonging to any private person or persons unless the same shall be agreed to and approved of by at least four of the said commissioners; and in every such case, that the damages sustained, or to be sustained, by reason thereof, by such private owner or owners, shall be valued and appraised by two indifferent persons, one of them to be chosen by the said commissioners, and the other by such owner or owners; and also that the said damages shall be paid to such owner, by order of the said commissioners, out of the moneys arising by virtue of this act.
53 P.S. § 16557