53 Pa. Stat. § 25011
In all tenement houses hereafter erected, wherever a connection with the city water main is in any way possible (and of this possibility the bureau of health shall be the judge) there shall be an independent water supply, and at least one sink for every tenement or suite of rooms; and in every now existing tenement house or house that may be hereafter converted into a tenement house, there shall be on every floor at least one proper sink, with running water, accessible to all the tenants of that floor without passing through any other apartment, if there be no such sink in each apartment; and the space under all sinks, and also under all bath tubs where such exist, shall be left entirely open, with no woodwork enclosing the same.
53 P.S. § 25011