53 Pa. Stat. § 1865
Thirty days notice of assessments of the whole cost or part of the cost of any such improvement shall be given to each party assessed, either by service on the owner or his agent, or posted on the premises by the clerk or secretary of the city, borough or township making the improvement. If any assessment shall remain unpaid at the expiration of the notice, it shall be the duty of the city, borough or township solicitor, as the case may be, to collect the same, with interest from the time of the completion of the improvement, by action of assumpsit, or by a lien to be filed and collected in the same manner as municipal claims. When an owner has two or more lots against which there is an assessment for the same improvement, all of such lots shall be embraced in one claim.
53 P.S. § 1865