Plumbing Code by State: IPC vs UPC
There is no national plumbing code in the US. Two model codes compete, states adopt one with amendments on their own schedule, and the edition your jurisdiction is on decides which sizing tables apply to your job.
The Two Model Codes
IPC — International Plumbing Code
Published by the International Code Council (ICC)
- Part of the I-Codes family, alongside the IBC and IRC
- Revised on a three-year cycle
- Water distribution sizing in Chapter 6, drainage in Chapter 7
- Generally the more common adoption in the eastern and central US
UPC — Uniform Plumbing Code
Published by IAPMO, developed under ANSI consensus
- Developed through an ANSI-accredited consensus process
- Also revised on a three-year cycle
- Differs from IPC on sizing tables, approved materials and venting
- Generally the more common adoption in the western US
A design sized against one code is not automatically compliant under the other. The regional tendencies above are tendencies, not rules — confirm the adoption for your specific jurisdiction.
State Adoptions
Which model code each state builds on, who administers it, and what catches people out. Edition years are shown only where verified against the state authority — they change on three-year cycles, and a stale year here would be worse than none.
| State | Code document | Based on | Authority |
|---|---|---|---|
| California | California Plumbing Code (CPC), Title 24 Part 5 | UPC | California Building Standards Commission |
| Texas | No single statewide code — municipalities adopt IPC or UPC | IPC | Texas Department of Licensing and Regulation (TDLR) |
| Illinois | Illinois Plumbing Code, 77 Ill. Adm. Code 890 | State-written | Illinois Department of Public Health (IDPH) |
| Massachusetts | Massachusetts State Plumbing and Gas Fitting Code, 248 CMR | State-written | Board of State Examiners of Plumbers and Gas Fitters |
| Wisconsin | Wisconsin Uniform Plumbing Code, SPS 382 | State-written | Wisconsin Department of Safety and Professional Services (DSPS) |
| New York | Plumbing Code of New York State | IPC | NYS Division of Building Standards and Codes |
California
UPC baseCalifornia Plumbing Code (CPC), Title 24 Part 5 — administered by the California Building Standards Commission. Licensing: Contractors State License Board (CSLB).
California writes its own code on a UPC base and publishes it inside Title 24, so the CPC is cited rather than the UPC directly. Amendments are substantial.
- Title 24 is republished on a three-year cycle with an intervening intermediate code adoption cycle, so the CPC can change between full editions. Check both.
- California amends the UPC base heavily around seismic bracing and water conservation; fixture flow-rate limits are stricter than the model code.
- Local jurisdictions in California may adopt amendments more restrictive than the state code but must file them with the state to be enforceable.
Texas
IPC baseNo single statewide code — municipalities adopt IPC or UPC — administered by the Texas Department of Licensing and Regulation (TDLR). Licensing: Texas State Board of Plumbing Examiners, now administered by TDLR.
Texas is unusual: both IPC and UPC are permitted, and the choice is made locally. Confirm which one your municipality enforces before sizing.
- Because both IPC and UPC are permitted, the same design can be compliant in one Texas city and rejected in the next. Establish which code the municipality enforces before sizing anything.
- Licensing is statewide through TDLR even though code enforcement is local, so a license valid in Houston is valid in El Paso while the applicable code may not be.
- Unincorporated areas may have no municipal plumbing code adoption at all, in which case state licensing rules still apply to who may perform the work.
Illinois
State-written codeIllinois Plumbing Code, 77 Ill. Adm. Code 890 — administered by the Illinois Department of Public Health (IDPH).
Illinois writes its own plumbing code rather than adopting IPC or UPC, and administers it through the health department rather than a building department. Sizing tables differ from both model codes.
- Administered by the Department of Public Health rather than a building department, which means plan review and inspection run through a different channel than in most states.
- Because the code is state-written, IPC and UPC sizing tables do not transfer. Fixture unit values and pipe sizing must come from 77 Ill. Adm. Code 890 itself.
- Chicago enforces its own municipal plumbing code separately from the state code.
Massachusetts
State-written codeMassachusetts State Plumbing and Gas Fitting Code, 248 CMR — administered by the Board of State Examiners of Plumbers and Gas Fitters.
Massachusetts neither adopts IPC nor UPC. The board writes 248 CMR directly, and it is among the more restrictive US codes on approved materials.
- 248 CMR is written directly by the plumbing board rather than adapted from a model code, so neither IPC nor UPC tables apply. This catches out-of-state contractors more than any other single difference.
- Approved materials are more restrictive than the model codes; materials routinely accepted elsewhere may not be permitted.
- The same board covers gas fitting, so gas and plumbing licensing are administered together.
Wisconsin
State-written codeWisconsin Uniform Plumbing Code, SPS 382 — administered by the Wisconsin Department of Safety and Professional Services (DSPS).
Despite the name, SPS 382 is a Wisconsin-written code, not the IAPMO Uniform Plumbing Code. Do not size from UPC tables here.
- The name is the trap: SPS 382 is called the Wisconsin Uniform Plumbing Code but it is not the IAPMO Uniform Plumbing Code. Sizing from IAPMO UPC tables here produces non-compliant designs.
- Administered by DSPS as an administrative rule, so revisions follow the state rulemaking process rather than a code publication cycle.
- Wisconsin has distinctive provisions for private onsite wastewater treatment systems, covered under a separate chapter from building drainage.
New York
IPC basePlumbing Code of New York State — administered by the NYS Division of Building Standards and Codes.
New York City is outside this code and enforces its own NYC Plumbing Code. For work in the five boroughs the state code does not apply.
- New York City is fully carved out and enforces the NYC Plumbing Code. For work in the five boroughs the state code does not apply at all, and NYC licensing is separate.
- Outside the city the Plumbing Code of New York State applies statewide, but many municipalities add local amendments.
- The state code is maintained by the Division of Building Standards and Codes on its own adoption schedule.
Confirm the edition before you size
No edition years are asserted above. Editions change on three-year cycles and states adopt on their own schedule, so a stale year is the most common way this kind of reference goes wrong — and sizing against the wrong edition fails plan review. Confirm with the authority named for your state.
Calculators That Cite Their Code
Code References & Best Practices:
- International Plumbing Code (IPC) — published by the International Code Council on a three-year revision cycle.
- Uniform Plumbing Code (UPC) — published by IAPMO under an ANSI-accredited consensus process, also on a three-year cycle.
- Adoption is a state function in the United States; there is no federally mandated plumbing code.
- Local jurisdictions frequently amend the state-adopted code. The authority having jurisdiction governs.
Frequently Asked Questions
Is there a national plumbing code in the United States?
No. There is no federally adopted plumbing code. Codes are published by private organisations and then adopted, with amendments, by individual states and in many cases by counties and cities. Two states can therefore require different pipe sizes for the same fixture count.
What is the difference between the IPC and the UPC?
They are competing model codes. The International Plumbing Code is published by the International Code Council and forms part of the I-Codes family alongside the IBC and IRC. The Uniform Plumbing Code is published by IAPMO and is developed under an ANSI consensus process. They differ in sizing tables, approved materials and venting methods, so a design that passes in an IPC state may not pass in a UPC state.
Why does the adopted edition matter and not just the code family?
Because tables change between editions. Both codes are revised on a three-year cycle, and states adopt on their own schedule — so some are several editions behind the current publication. Sizing against the current edition when your jurisdiction is on an older one is a common cause of failed plan review.
Can a city require something stricter than the state code?
Yes, in most states. Local amendments commonly tighten requirements around backflow prevention, materials permitted in specific occupancies, and minimum trap sizes. The authority having jurisdiction always governs, so confirm locally before submitting for permit.
Which code do plumbing calculators use?
It depends on the tool, and that is worth checking before you rely on one. Our sizing calculators state the edition and table used, because a number produced against the wrong code is worse than no number at all.