Definitions Both Codes Agree On — Drainage, Venting, Water Supply and Backflow Vocabulary (UPC ch. 2 / IPC ch. 2)
Texas adopts both the 2018 UPC and the 2018 IPC (22 TAC 367.2), and the TSBPE exams are written so a candidate who knows either code can pass. That is why this lesson teaches the definitions where the two codes say the same thing and flags, in one place at the end, the handful where they differ — those never appear in our question bank.
2018 UPC and 2018 IPC · Reviewed 2026-09-20
Both chapters open the same way: the chapter's meanings govern unless the code expressly says otherwise; a term the code does not define takes its ordinary meaning in context (UPC 201.0–202.0; IPC 201.1–201.4). The IPC adds that terms defined in the IBC, IFC, IFGC or IMC keep those meanings; the UPC imports NFPA 54/70/99 definitions for fuel gas, electrical and medical gas.
Where to find a term: UPC chapter 2 is alphabetical by section — 203.0 = A, 204.0 = B, 205.0 = C … 218.0 = P … 225.0 = W, 227.0 = Y (each letter has its own section number). Every IPC definition lives in Section 202 (general definitions), also alphabetical.
1. Drainage piping — from the fixture to the street
| Term | What it means (both codes) | UPC | IPC |
|---|---|---|---|
| Fixture drain | the drain from a fixture's trap to its junction with any other drain pipe | 208.0 | 202 |
| Branch | any part of the piping other than a main, riser or stack | 204.0 | 202 |
| Main | the principal artery of a piping system, to which branches connect | 215.0 | 202 |
| Stack | the vertical main (line) of soil, waste or vent piping running through one or more stories | 221.0 | 202 |
| Soil pipe | carries sewage containing fecal matter (water closets, urinals, clinical sinks) to the building drain or sewer | 221.0 | 202 |
| Waste pipe | carries only liquid waste — no fecal matter | 225.0 | 202 |
| Building drain | the lowest piping of the drainage system; receives the soil, waste and other drainage pipes inside the building walls and carries the discharge to the building sewer | 204.0 | 202 |
| Building sewer | the piping from the end of the building drain to the public sewer, private sewer, private/individual sewage disposal system or other disposal point | 204.0 | 202 |
| **Buil |
This is where the public part ends.
The rest of this lesson, its quiz, all 1 lessons in the module and every mock exam open with the 7-day pass for $9. If you stay, it comes off lifetime.