8.1 Sanitary Drainage Materials and Where Each May Be Used
Key Takeaways
- IPC Table 702.1 governs above-ground sanitary drainage and vent pipe, Table 702.2 governs underground building drainage and vent pipe, and Table 702.3 governs building sewer pipe.
- IPC 702.5 requires drainage piping to have a rated working temperature of not less than 140 degrees F, and 180 degrees F where it receives discharge above 140 degrees F.
- IPC 702.6 requires chemical waste to discharge to a separate drainage system, independent of the sanitary drainage system.
- IPC 702.7 requires lead bends and traps to have a wall thickness of not less than 0.125 inch.
- IPC 701.2 requires every plumbing fixture, drain, appurtenance and appliance to be connected to a sanitary sewer, or to an approved private sewage disposal system.
Why this area carries twenty items
Sanitary Drainage is the single heaviest content area on the exam. Twenty of one hundred scored items come from IPC Chapter 7 and the parallel IRC Chapter 30. This guide splits that weight across three chapters: materials and fittings here, sizing in Chapter 9, and cleanouts, sumps and below-sewer drainage in Chapter 10.
IPC 701.1 sets the scope: Chapter 7 governs materials, design, construction and installation of sanitary drainage systems.
Connection to the sewer — IPC 701.2
Every plumbing fixture, drain, appurtenance and appliance shall be connected to a sanitary sewer or to an approved private sewage disposal system in accordance with this code.
701.3 Separate sewer connection: a building with more than one sewer connection, or a building having plumbing on more than one lot, must have a separate connection for each lot or building as required by the administrative authority.
701.4 Sewage treatment: sewage or other waste from a plumbing system deleterious to surface or subsurface waters shall not be discharged into the ground or into any waterway unless first rendered innocuous by approved treatment.
701.5 Damage to drainage system or public sewer: waste detrimental to the public sewer or to the functioning of the sewage treatment plant shall be treated and disposed of as directed by the code official.
701.6 Tests: drainage and vent systems are tested per IPC 312.
701.7 Engineered systems: engineered drainage design complies with IPC 316.1.
Colorado field note (not exam-scored): Board Rule 1.2(E)(1)(ii) adds an exception to 701.2 permitting floor drains or trench drains in utility buildings and residential garages to be daylighted or discharged to an approved alternative disposal system when written approval has been provided by the jurisdiction having authority through CDPHE or the sewer purveyor.
Three material tables, three applications
The single most common material mistake is applying the wrong table. Read the table title before the material list.
| Table | Application |
|---|---|
| 702.1 | Above-ground sanitary drainage and vent pipe |
| 702.2 | Underground building sanitary drainage and vent pipe |
| 702.3 | Building sewer pipe |
| 702.4 | Pipe fittings |
What is listed where
| Material | Above ground (702.1) | Underground (702.2) | Building sewer (702.3) |
|---|---|---|---|
| ABS plastic DWV | yes | yes | yes |
| PVC plastic DWV | yes | yes | yes |
| Cast-iron pipe | yes | yes | yes |
| Copper or copper-alloy pipe | yes | yes | yes |
| Copper or copper-alloy tubing (Type K, L, M or DWV) | yes | yes | yes |
| Galvanized steel pipe | yes | no | no |
| Brass pipe | yes | no | no |
| Glass pipe (borosilicate) | yes | no | no |
| Stainless steel drainage systems, Type 316L | yes | yes | yes |
| Polyolefin / PVDF / polypropylene (chemical waste) | yes | yes | — |
| Concrete pipe | no | no | yes |
| Vitrified clay pipe | no | no | yes |
| Polyethylene (PE) plastic pipe | no | no | yes |
| Ductile iron | — | — | yes |
The pattern to hold on to: galvanized steel, brass and glass are above-ground materials only, and concrete, vitrified clay and PE are building-sewer materials only. ABS, PVC, cast iron, copper and stainless run through all three tables.
IPC 703.2 Drainage pipe in filled ground: where a building drain or sewer is installed on filled or unstable ground, it must be of materials listed in Table 702.2 or 702.3 — the more robust underground materials.
IPC 703.4: existing building sewers and drains may be used in connection with new systems only where found on examination and test to conform to the new system in quality of material. This is the rule that decides whether an old clay sewer may be reused after a remodel.
Temperature rating — IPC 702.5
Where the drainage piping is to receive discharge of liquid waste at a temperature greater than 140 degrees F, the piping shall have a rated working temperature of not less than 180 degrees F.
The default expectation is 140 degrees F. Standard PVC and ABS DWV are rated for continuous service well below the boiling point, which is why a commercial dishwasher, a sterilizer or a boiler blowdown line typically discharges through an indirect waste to a receptor (IPC Chapter 8) rather than directly into plastic drainage.
Chemical waste — IPC 702.6
Where a chemical waste is discharged to the drainage system, the chemical waste shall discharge to a separate drainage system, independent of the sanitary drainage system.
Chemical waste piping materials are listed in Table 702.1 and 702.2 — polyolefin, PVDF, borosilicate glass and similar chemically resistant systems. IPC 803 requires corrosive liquids and harmful chemicals to be neutralized to a pH between 6.0 and 8.0 through an approved dilution or neutralizing device before discharge.
IPC 702.7 Lead bends and traps: lead bends and traps shall have a wall thickness of not less than 0.125 inch.
Building sewer installation
| Section | Rule |
|---|---|
| 703.1 | Where the building sewer is within 5 feet of the water service, comply with the separation requirements of 603.2 — 5 feet of undisturbed earth, or Table 702.2 materials, or the crossing/elevation exceptions |
| 703.2 | Filled or unstable ground requires Table 702.2 or 702.3 materials |
| 703.3 | Sanitary and storm sewers shall be separate where the public sewer system is separate |
| 703.4 | Existing sewers and drains reused only where they conform in quality of material |
| 703.5 | Cleanouts on building sewers per Section 708 |
| 703.6 | Where the public sewer is a combined system, the storm sewer connects independently to the public sewer |
Recall IPC 305.4.1 Sewer depth is a bracketed section in the model code — the depth numbers are filled in by the adopting jurisdiction. In Colorado, sewer bury depth is a local determination, not a statewide number.
Pipe bursting — IPC Section 716
A modern section worth knowing because it appears on newer exam forms:
- Limited to gravity drainage piping 6 inches and smaller; the replacement pipe is the same nominal size as the existing piping.
- Pre-installation: the piping to be replaced must be inspected internally by a recorded video camera survey, noting cleanout positions and connection depths.
- Pipe: high-density polyethylene (HDPE) with a standard dimension ratio (SDR) of 17, complying with ASTM F714.
- Fittings: HDPE complying with ASTM D2683.
- Cleanouts: where the existing sewer or drain lacked compliant cleanouts, cleanout fittings must be installed as the code requires.
- Post-installation: another recorded video camera survey.
Vacuum drainage — IPC Section 715
Designed to the manufacturer's instructions with plans submitted for approval. Two numbers to remember:
- The completed system is subjected to a vacuum test of 19 inches of mercury (715.3).
- The water supply fixture unit value for a vacuum-type water closet is 1 (715.2.3) — dramatically lower than the 2.2 to 10 wsfu of a conventional water closet, because a vacuum closet uses roughly a pint of water per flush.
Drainage fixture units for gravity fixtures in a vacuum system are still based on the Chapter 7 values, and gravity fixtures still need traps and cleanouts per Chapters 7 and 10.
Computerized drainage design — IPC Section 713
Where a drainage system is designed by approved computer design methods, the load is computed from simultaneous or sequential discharge conditions or the peak usage design condition, with fixture discharge profiles from the manufacturer's specifications. Two constraints survive the computer:
- 713.3: pipe shall be sized to prevent full-bore flow.
- 713.3.2: horizontal drainage piping is still installed at the slopes in Table 704.1.
Which material is listed for building sewer pipe but NOT for above-ground sanitary drainage pipe?
Drainage piping will receive liquid waste at a temperature greater than 140 degrees F. What rated working temperature does IPC 702.5 require?
Where must chemical waste discharge under IPC 702.6?
Under IPC 716, replacement of a building sewer by pipe-bursting methods is limited to gravity drainage piping of what size, using what pipe material?