53 Pa. Stat. § 4606
Materials of House or Building Drains. The main drainage system of every house or building shall be separately and independently connected with the street sewer, where such sewer exists, except where two houses are built together on a lot with a frontage of thirty feet or less, when one connection with main sewer will be allowed; but there shall be a separate house for each house, connected by a "Y" connection in the front of such houses, at the property line, with main house sewer; or, where one building exists or is erected in the rear of another, on an interior lot, of single ownership, and no private sewer is available, or can be made for the rear building through an adjoining alley, courtyard or driveway, the house drain from the front building may be extended to the rear building, and the whole will be considered as one house or building drain. Where it is necessary to construct a private sewer to connect with sewer on adjacent street, such plans may be used as may be approved by the department or board or bureau of health, but in no case shall joint drains be laid in cellars, parallel with the street or alley.
Drains or soil pipes, laid beneath floor, must be extra heavy cast-iron pipe (as per table in section 16), with leaded and caulked joints, and carried five feet outside cellar wall. All drains or soil pipes connected with main drain where it is above the cellar floor shall be of extra heavy cast-iron pipe, with leaded and caulked joints, or of heavy wrought-iron pipe, with screw joints properly secured, and carried five feet outside of cellar wall, and all arrangements of soil or waste pipes shall be as direct as possible. All genuine wrought-iron, wrought-steel or copperized iron pipes shall be galvanized. Changes of direction on pipes shall be made with "Y" branches, both above and below the ground, and where such pipes pass through a new foundation wall a relieving arch shall be built over it, with two inch space on either side of main pipe.
The size of the main house drain shall be determined by the total area of the buildings and paved surfaces to be drained, according to the following table, if iron pipe is used. If the pipe is terra cotta, the diameter shall be one size larger for the same amount of area drainage.
Diameter. | Fall 1/4 Inch Per Foot. | Fall 1/2 Inch Per Foot. |
4 inches, | 1,800 square ft. drainage area, | 2,500 square ft. drainage area. |
5 inches, | 3,000 square ft. drainage area, | 4,500 square ft. drainage area. |
6 inches, | 5,000 square ft. drainage area, | 7,500 square ft. drainage area. |
8 inches, | 9,100 square ft. drainage area, | 13,600 square ft. drainage area. |
10 inches, | 14,000 square ft. drainage area, | 20,000 square ft. drainage area. |
The main house drains may be decreased in diameter beyond a rain-water conductor or surface inlet by permission of the department or board or bureau of health, when the plans show that conditions are such as to warrant such decrease; but in no case shall the main house drain be less than four (4) inches in diameter.
53 P.S. § 4606