ADOPTS WITH AMENDMENTS:

International Plumbing Code 2018 (IPC 2018)

Heads up: There are no amended sections in this chapter.

User note:

About this chapter: Rainfall onto buildings must be removed and directed to a location that can accommodate storm water. Chapter 11 specifies the design rainfall event for the geographic area and provides sizing methods for piping and gutter systems to convey the storm water away from the building. Included in this chapter are regulations for piping materials and subsoil drainage systems.

The provisions of this chapter shall govern the materials, design, construction and installation of storm drainage.

1101.2 P-1101.2 Disposal

AMENDMENT
This section has been amended at the state or city level.
All rainwater from roofs and storm water from paved areas, yards, courts and courtyards shall drain to an approved place of disposal. For one- and two-family dwellings, and where approved, storm water is permitted to discharge onto flat pervious areas, such as lawns, or area drains provided that the storm water flows away from the building.

P-1101.2.1 Area Drain

AMENDMENT
This section has been amended at the state or city level.
Area drains shall be provided on all premises in the locations required by Items 1 through 6 below:
  1. Paved areas, courts, open shafts in excess of 5,000 square feet (465 m2).
  2. Driveways of any area which slope downward toward the building.
  3. Terrain which slopes downward toward the building within 10 feet (3048 mm) of the building's exterior walls.
  4. Terrain which creates a low elevation such that standing water is possible.
  5. Terrain which slopes downward toward adjacent property in such a manner as to concentrate the flow of runoff.

    Exception: Where terrain slopes toward a natural watercourse such as a creek, stream or river, an area drain shall not be required.
  6. At the low point of any swales on the property.

    Exception: Where terrain slopes toward a natural watercourse such as a creek, stream or river, an area drain shall not be required.
Storm water shall not be drained into sewers intended for sewage only.
The conductors and the building storm drain shall be tested in accordance with Section 312.
The size of a drainage pipe shall not be reduced in the direction of flow.
Connections and changes in direction of the storm drainage system shall be made with approved drainage-type fittings in accordance with Table 706.3. The fittings shall not obstruct or retard flow in the system.
Roofs shall be designed for the maximum possible depth of water that will pond thereon as determined by the relative levels of roof deck and overflow weirs, scuppers, edges or serviceable drains in combination with the deflected structural elements. In determining the maximum possible depth of water, all primary roof drainage means shall be assumed to be blocked. The maximum possible depth of water on the roof shall include the height of the water required above the inlet of the secondary roof drainage means to achieve the required flow rate of the secondary drainage means to accommodate the design rainfall rate as required by Section 1106.

Cleanouts shall be installed in the storm drainage system and shall comply with the provisions of this code for sanitary drainage pipe cleanouts.

Exception: Subsurface drainage system.

1101.9 P-1101.9 Backwater Valves

AMENDMENT
This section has been amended at the state or city level.

Storm drainage systems shall be provided with backwater valves as required for sanitary drainage systems in accordance with Section 714.

Exception: Storm drainage systems and private on-site storm water management systems located outside the 100-year flood plain or connected to the public storm sewer.
The materials and methods utilized for the construction and installation of storm drainage systems shall comply with this section and the applicable provisions of Chapter 7.

1102.2 P-1102.2 Inside Storm Drainage Conductors

AMENDMENT
This section has been amended at the state or city level.
Inside storm drainage conductors installed above ground shall conform to one of the standards listed in Section 702.1.

1102.3 P-1102.3 Underground Building Storm Drain Pipe

AMENDMENT
This section has been amended at the state or city level.
Underground building storm drain pipe shall conform to one of the standards listed in Section 702.2.

1102.4 Building Storm Sewer Pipe

AMENDMENT
This section has been amended at the state or city level.

Building storm sewer pipe shall conform to one of the standards listed in Table 1102.4.

TABLE P-1102.4
BUILDING STORM SEWER PIPE

MATERIAL STANDARD
Acrylonitrile butadiene styrene (ABS) plastic pipe in IPS diameters, including Schedule 40, DR 22 (PS 200) and DR 24 (PS 140); with a solid, cellular core or composite wall.
ASTM D2661; ASTM F628; ASTM F1488; CSA B181.1; CSA B182.1
Cast-iron pipe ASTM A74
Concrete pipe ASTM C14; ASTM C76; CSA A257.1M; CSA A257.2M
Copper or copper-alloy tubing (Type K, L, M or DWV)
ASTM B75; ASTM B88; ASTM B251; ASTM B306
Ductile iron pipe AWWA C151/A21.51; AWWA C115/A21.15
Polyethylene (PE) plastic pipe ASTM F667; ASTM F2306/F2306M; ASTM F2648/F2648M
Polypropylene (PP) pipe ASTM F2881; CSA B182.13
Polyvinyl chloride (PVC) plastic pipe (Type DWV, SDR26, SDR35, SDR41, PS50 or PS100) in IPS diameters, including Schedule 40, DR 22 (PS 200) and DR 24 (PS 140); with a solid, cellular core or composite wall.
ASTM D2665; ASTM D3034; ASTM F891; ASTM F1488; CSA B182.4; CSA B181.2; CSA B182.2
Vitrified clay pipe ASTM C4; ASTM C700
Stainless steel drainage systems, Type 316L
ASME A112.3.1

1102.5 Subsoil Drain Pipe

AMENDMENT
This section has been amended at the state or city level.

Subsoil drains shall be open-jointed, horizontally split or perforated pipe conforming to one of the standards listed in Table 1102.5.

TABLE 1102.5
SUBSOIL DRAIN PIPE

MATERIALSTANDARD
Cast-iron pipeASTM A74; CISPI 301
Polyethylene (PE) plastic pipeASTM F405; ASTM F667; CSA B182.1; CSA B182.6; CSA B182.8
Polyvinyl chloride (PVC) Plastic pipe (type sewer pipe, SDR35, PS25, PS50 or PS100)ASTM D2729; ASTM D3034, ASTM F891; CSA B182.2; CSA B182.4
Stainless steel drainage systems, Type 316LASME A112.3.1
Vitrified clay pipeASTM C4; ASTM C700

1102.6 P-1102.6 Roof Drains

AMENDMENT
This section has been amended at the state or city level.
Roof drains shall conform to ASME A112.6.4 or ASME A112.3.1. Roof drain materials shall comply with Sections 1102.2 and 702.1.

Pipe fittings shall be approved for installation with the piping material installed, and shall conform to the respective pipe standards or one of the standards listed in Table 1102.7. The fittings shall not have ledges, shoulders or reductions capable of retarding or obstructing flow in the piping. Threaded drainage pipe fittings shall be of the recessed drainage type.

TABLE 1102.7

PIPE FITTINGS

MATERIALSTANDARD
Acrylonitrile butadiene styrene (ABS) plasticASTM D2661; ASTM D3311; CSA B181.1
Cast-ironASME B16.4; ASME B16.12; ASTM A888; CISPI 301; ASTM A74
Coextruded composite ABS and drain DR-PS in PS35, PS50, PS100, PS140, PS200ASTM D2751
Coextruded composite ABS DWV Schedule 40 IPS pipe (solid or cellular core)ASTM D2661; ASTM D3311; ASTM F628
Coextruded composite PVC DWV Schedule 40 IPS-DR, PS140, PS200 (solid or cellular core)ASTM D2665; ASTM D3311; ASTM F891
Coextruded composite PVC sewer and drain DR-PS in PS35, PS50, PS100, PS140, PS200ASTM D3034
Copper or copper alloyASME B16.15; ASME B16.18; ASME B16.22; ASME B16.23; ASME B16.26; ASME B16.29
Gray iron and ductile ironAWWA C110/A21.10
Malleable ironASME B16.3
Plastic, generalASTM F409
Polyethylene (PE) plastic pipeASTM F2306/F2306M
Polyvinyl chloride (PVC) plasticASTM D2665; ASTM D3311; ASTM F1866
SteelASME B16.9; ASME B16.11; ASME B16.28
Stainless steel drainage systems, Type 316LASME A112.3.1

1103.1 P-1103.1 Main Trap

AMENDMENT
This section has been amended at the state or city level.
Leaders and storm drains connected to a combined sewer shall be trapped. Individual storm water traps shall be installed on the storm water drain branch serving each conductor, or a single trap shall be installed in the main storm drain just before its connection with the combined building sewer or the public sewer. A single hooded catch basin located within the property line shall be the equivalent of a building (house) trap for the connection to a street combined sewer. Leaders and storm drains connected to a building storm sewer shall not be required to be trapped.
Storm water traps shall be of the same material as the piping system to which they are attached.
Traps for individual conductors shall be the same size as the horizontal drain to which they are connected.

1103.4 Cleanout

AMENDMENT
This section has been amended at the state or city level.

P-1103.4 Cleanout

AMENDMENT
This section has been amended at the state or city level.
A cleanout or a building storm sewer house trap shall be required on a dedicated storm sewer system where the building storm sewer connects at the curb.
Conductor pipes shall not be used as soil, waste or vent pipes, and soil, waste or vent pipes shall not be used as conductors.
Floor drains shall not be connected to a storm drain.
Roof drains shall be installed in accordance with the manufacturer's instructions. The inside opening for the roof drain shall not be obstructed by the roofing membrane material.
The published roof drain flow rate, based on the head of water above the roof drain, shall be used to size the storm drainage system in accordance with Section 1106. The flow rate used for sizing the storm drainage piping shall be based on the maximum anticipated ponding at the roof drain.

1106.1 P-1106.1 General

AMENDMENT
This section has been amended at the state or city level.
The size of the vertical conductors and leaders, building storm drains, building storm sewers and any horizontal branches of such drains or sewers shall be based on a rainfall rate of 4.5 inches (114 mm) per hour.

Exceptions:
  1. Existing building storm drainage systems without secondary roof drainage installed in accordance with Section 1108 shall be designed based on a rainfall rate of 6 inches (152 mm) per hour.
  2. The size of building storm drainage systems serving green roof systems, approved by the Philadelphia Water Department, shall be based on a rainfall rate of 3.1 inches (79 mm) per hour.


Figure 1106.1 Reserved.

Vertical and horizontal storm drain piping shall be sized based on the flow rate through the roof drain. The flow rate in storm drain piping shall not exceed that specified in Table 1106.2.

TABLE 1106.2

STORM DRAIN PIPE SIZING

PIPE SIZE
(inches)
CAPACITY (gpm)
VERTICAL DRAINSLOPE OF HORIZONTAL DRAIN
1/16 inch per foot1/8 inch per foot1/4 inch per foot1/2 inch per foot
23415223144
387395579111
418081115163231
5311117165234331
6538243344487689
81,1175057141,0101,429
102,0509271,3111,8552,623
123,2721,4802,0932,9604,187
155,5432,5083,5465,0167,093

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 gallon per minute = 3.785 L/m.

Vertical leaders shall be sized based on the flow rate from horizontal gutters or the maximum flow rate through roof drains. The flow rate through vertical leaders shall not exceed that specified in Table 1106.3.

TABLE 1106.3

VERTICAL LEADER SIZING

SIZE OF LEADER
(inches)
CAPACITY
(gpm)
230
2 × 230
11/2 × 21/230
21/254
21/2 × 21/254
392
2 × 492
21/2 × 392
4192
3 × 41/4192
31/2 × 4192
5360
4 × 5360
41/2 × 41/2360
6563
5 × 6563
51/2 × 51/2563
81208
6 × 81208

For SI: 1 inch = 25.4 mm, 1 gallon per minute = 3.785 L/m.

In sizing roof drains and storm drainage piping, one-half of the area of any vertical wall that diverts rainwater to the roof shall be added to the projected roof area for inclusion in calculating the required size of vertical conductors, leaders and horizontal storm drainage piping.
Where scuppers are used for primary roof drainage or for secondary (emergency overflow) roof drainage or both, the quantity, size, location and inlet elevation of the scuppers shall be chosen to prevent the depth of ponding water on the roof from exceeding the maximum water depth that the roof was designed for as determined by Section 1611.1 of the International Building Code. Scupper openings shall be not less than 4 inches (102 mm) in height and have a width that is equal to or greater than the circumference of a roof drain sized for the same roof area. The flow through the primary system shall not be considered when locating and sizing secondary scuppers.

Horizontal gutters shall be sized based on the flow rate from the roof surface. The flow rate in horizontal gutters shall not exceed that specified in Table 1106.6.

TABLE 1106.6

HORIZONTAL GUTTER SIZING

GUTTER DIMENSIONSa
(inches)
SLOPE
(inch per foot)
CAPACITY
(gpm)
11/2 × 21/21/426
11/2 × 21/21/240
41/839
21/4 × 31/455
21/4 × 31/287
51/874
4 × 21/21/4106
3 × 31/21/2156
61/8110
3 × 51/4157
3 × 51/2225
81/16172
81/8247
41/2 × 61/4348
41/2 × 61/2494
101/16331
101/8472
5 × 81/4651
4 × 101/21055

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 gallon per minute = 3.785 L/m, 1 inch per foot = 83.3 mm/m.

  1. Dimensions are width by depth for rectangular shapes. Single dimensions are diameters of a semicircle.

1107.1 P-1107.1 General

AMENDMENT
This section has been amended at the state or city level.
Siphonic roof drains and drainage systems shall be prohibited.
Where roof drains are required, secondary (emergency overflow) roof drains or scuppers shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason. Where primary and secondary roof drains are manufactured as a single assembly, the inlet and outlet for each drain shall be independent.
Secondary roof drain systems shall have the end point of discharge separate from the primary system. Discharge shall be above grade, in a location that would normally be observed by the building occupants or maintenance personnel.
Secondary (emergency) roof drain systems shall be sized in accordance with Section 1106 based on the rainfall rate for which the primary system is sized. Scuppers shall be sized to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by Section 1101.7. Scuppers shall have an opening dimension of not less than 4 inches (102 mm) in height and have an opening width equal to the circumference of the roof drain required for the area served. The flow through the primary system shall not be considered when sizing the secondary roof drain system.

1109.1 P-1109.1 General

AMENDMENT
This section has been amended at the state or city level.
Where the public sewer is a combined system for both sanitary and storm water, the storm sewer shall be connected independently to the lateral.

Exception: The repair or replacement of an existing combined building sewer as of the initial adoption date of this code.

P-1109.2 Size of the Existing Combined Building Drains and Building Sewers

AMENDMENT
This section has been amended at the state or city level.
The size of the existing combined building drains and building sewers when being replaced in kind shall not be less than 4 inches (102 mm) and not have a slope less than 1/8 inch per foot (10.4 mm/m) (1 percent).

P-1109.3 Size of Existing Combined Building Drains and Building Sewers When Adding Additional Load

AMENDMENT
This section has been amended at the state or city level.
The size of a combination sanitary and storm drain or sewer shall be computed in accordance with the method in Table 1109.4. The fixture units shall be converted into an equivalent projected roof or paved area. Where the total fixture load on the combined drain is less than or equal to 256 fixture units, the equivalent drainage area in horizontal projection shall be taken as 4,000 square feet (372 m2). Where the total fixture load exceeds 256 fixture units, each additional fixture unit shall be considered the equivalent of 15.6 square feet (1.5 m2) of drainage area. These values are based on a rainfall rate of 6 inches (127 mm) per hour.

TABLE P-1109.4
SIZE OF HORIZONTAL STORM DRAINAGE PIPING
SIZE OF HORIZONTAL PIPE HORIZONTALLY PROJECTED ROOF AREA
(square feet)
1/8 unit vertical in 12 units horizontal (1% slope)
3 548
4 1,253
5 2,227
6 3,566
8 7,600
10 13,800
12 22,200
15 39,650
1/4 unit vertical in 12 units horizontal (2% slope)
3 773
4 1,766
5 3,146
6 5,033
8 10,866
10 19,450
12 31,350
15 56,000
1/2 unit vertical in 12 units horizontal (4% slope)
3 1,096
4 2,500
5 4,450
6 7,140
8 15,320
10 27,600
12 44,400
15 79,250
For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m2.
The roof of a structure shall be designed for the storage of water where the storm drainage system is engineered for controlled flow. The controlled flow roof drain system shall be an engineered system in accordance with this section and the design, submittal, approval, inspection and testing requirements of Section 316.1. The controlled flow system shall be designed based on the required rainfall rate in accordance with Section 1106.1.
The control devices shall be installed so that the rate of discharge of water per minute shall not exceed the values for continuous flow as indicated in Section 1110.1.
Runoff control shall be by control devices. Control devices shall be protected by strainers.
Not less than two roof drains shall be installed in roof areas 10,000 square feet (929 m2) or less and not less than four roof drains shall be installed in roofs over 10,000 square feet (929 m2) in area.
Subsoil drains shall be open-jointed, horizontally split or perforated pipe conforming to one of the standards listed in Table 1102.5. Such drains shall be not less than 4 inches (102 mm) in diameter. Where the building is subject to backwater, the subsoil drain shall be protected by an accessibly located backwater valve. Subsoil drains shall discharge to a trapped area drain, sump, dry well or approved location above ground. The subsoil sump shall not be required to have either a gas-tight cover or a vent. The sump and pumping system shall comply with Section 1113.1.
Building subdrains located below the public sewer level shall discharge into a sump or receiving tank, the contents of which shall be automatically lifted and discharged into the drainage system as required for building sumps. The sump and pumping equipment shall comply with Section 1113.1.
The sump pump, pit and discharge piping shall conform to Sections 1113.1.1 through 1113.1.4.

1113.1.1 P-1113.1.1 Pump Capacity and Head

AMENDMENT
This section has been amended at the state or city level.
The sump pump shall be of a capacity and head appropriate to anticipated use requirements.
The sump pit shall be not less than 18 inches (457 mm) in diameter and not less than 24 inches (610 mm) in depth, unless otherwise approved. The pit shall be provided with access and shall be located such that all drainage flows into the pit by gravity. The sump pit shall be constructed of tile, steel, plastic, cast iron, concrete or other approved material, with a removable cover adequate to support anticipated loads in the area of use. The pit floor shall be solid and provide permanent support for the pump.
Electrical service outlets, where required, shall meet the requirements of NFPA 70.

1113.1.4 P-1113.1.4 Piping

AMENDMENT
This section has been amended at the state or city level.

Discharge piping shall meet the requirements of Section 1102.2, 1102.3 or 1102.4 and shall include a full open valve and a full flow check valve. Pipe and fittings shall be the same size as, or larger than, the pump discharge tapping.

Exception: Reserved.

Section P-1114 Sustainable Green Roof Drainage Systems

AMENDMENT
This section has been amended at the state or city level.

P-1114.1 General

AMENDMENT
This section has been amended at the state or city level.
A green roof drainage system receiving storm water discharge solely from a green roof shall be engineered in accordance with this section and the design, submittal, approval, inspection and testing requirements of Section 316.1.

P-1114.2 Green Roof Design

AMENDMENT
This section has been amended at the state or city level.
Green roof designs shall comply with Section 1101.7. Support for the weight of the green roof system shall be accounted for in the building structural design and prepared by a licensed design professional for all new building construction and alterations or retrofits to existing structures.

P-1114.2.1 Green Roof Rainfall Rates

AMENDMENT
This section has been amended at the state or city level.
The green roof drainage system shall be designed based on the reduced rainfall rate in accordance with Section 1106.1 only where approved through the Philadelphia Water Department and shall satisfy the design, installation and maintenance requirements set forth by the Philadelphia Water Department storm water management regulations and, if applicable, the Philadelphia Zoning Code.

P-1114.3 Green Roof Drains

AMENDMENT
This section has been amended at the state or city level.
Roof drains serving green roofs shall conform to requirements of Chapter 11 and be protected with a means to prevent sediment and debris from entering the storm drainage piping system, including provisions for roof drain access for general maintenance.

Section P-1115 Private Storm Sewer Infrastructure

AMENDMENT
This section has been amended at the state or city level.

P-1115.1 General

AMENDMENT
This section has been amended at the state or city level.
The provisions of this section shall govern the materials, design and construction of private storm sewer infrastructure.

P-1115.1.1 Definitions

AMENDMENT
This section has been amended at the state or city level.
The following definitions shall apply to private storm sewer infrastructure.

PRIVATE SEWER INFRASTRUCTURE. The sewer pipe that is constructed on private property between the lateral and the building sewer owned and maintained by the unit owner's association to serve some or all units within a condominium or planned community.

Sanitary. Private sewer infrastructure that conveys sewage only.

Storm. Private sewer infrastructure that conveys storm water or other drainage, but not sewage.

P-1115.2 Materials

AMENDMENT
This section has been amended at the state or city level.
Private storm sewer infrastructure shall conform to Table 1102.4 of this code.

P-1115.3 Slope of Private Storm Sewer Infrastructure

AMENDMENT
This section has been amended at the state or city level.
Private storm sewer infrastructure shall be installed in uniform alignment at uniform slopes. The slope of private storm sewer infrastructure shall be in accordance with Table 704.1 of this code.

P-1115.4 Connections

AMENDMENT
This section has been amended at the state or city level.
The building storm sewers for each house or structure shall be connected to the private storm sewer infrastructure separately.

P-1115.5 Depth of Private Storm Sewer Infrastructure

AMENDMENT
This section has been amended at the state or city level.
Private storm sewer infrastructure shall be installed not less than 36 inches (914 mm) measured from the top of pipe.

P-1115.6 Access for Repairs

AMENDMENT
This section has been amended at the state or city level.
Separation of private water, sanitary sewer and storm sewer infrastructure placed in the same alignment and at a depth not exceeding 5 feet (1524 mm) shall comply with Section 603.2 of this code. Infrastructure placed at depths greater than 5 feet (1524 mm) shall be horizontally separated at a distance that allows for the approved sheeting and shoring and not less than 2 feet (610 mm).

P-1115.7 Protection of Structures

AMENDMENT
This section has been amended at the state or city level.
Private storm sewer infrastructure installed parallel to footings and walls shall not extend into the bearing plane of a footing or wall in accordance with Section 307.5 of this code. Private storm sewer infrastructure pipe shall not be installed within 5 feet (1524 mm) of any adjoining property building foundation

P-1115.8 Cleanouts Required

AMENDMENT
This section has been amended at the state or city level.
Cleanouts shall be provided for private storm sewer infrastructure in accordance with the provisions of this code for storm drainage pipe in Section 708.1. Where the public sewer is combined, all building sewers connected to private storm sewer infrastructure shall be fitted with an approved building trap and fresh air inlet. The sewer will not require a trap and fresh air inlet at the connection to the lateral but will require a manhole or cleanout at the property line before entering the public right-of-way.

P-1115.9 Manholes

AMENDMENT
This section has been amended at the state or city level.
Manholes will be required for private storm sewer infrastructure 8 inches (203 mm) in diameter and greater at changes in direction, grade and size. All manholes shall have inverts built with channels extending up to the pipe crown to ensure uniform flow in accordance with Section 708.1 of this code.

P-1115.10 Storm Backflow

AMENDMENT
This section has been amended at the state or city level.
Backwater valves shall be installed in accordance with Section 1101.9 of this code.

P-1115.11 Easement Required

AMENDMENT
This section has been amended at the state or city level.
Private Storm Sewer shall require an easement with a minimum width of 12' and must provide adequate space to replace/repair the private services. Minimum vertical drive height clearance of 13'-6" or 2x pipe depth to pipe bottom, whichever is greater, shall be provided.
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