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    IPC/UPC · free practice

    IPC / UPC Practice Questions — International & Uniform Plumbing Code

    Free practice questions on the International Plumbing Code (IPC, published by ICC) and the Uniform Plumbing Code (UPC, published by IAPMO). Every question is tagged with the code family it applies to, plus a section reference in the answer key. Roughly half the U.S. adopts one or the other (with state amendments); a few states publish their own derived code (CPC in California, OPSC in Oregon). Use this set to drill code-family-specific differences — air-admittance valves are an IPC concept, for instance, while the UPC has unique vent-sizing tables.

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    Sample questions

    1. The Uniform Plumbing Code (UPC) is published by:

    1. A. ICC (International Code Council)
    2. B. IAPMO (International Association of Plumbing and Mechanical Officials)
    3. C. NFPA
    4. D. ASME
    Show explanation

    IAPMO publishes the Uniform Plumbing Code (UPC). ICC publishes the competing International Plumbing Code (IPC). A jurisdiction adopts one family (sometimes with amendments) as its governing plumbing code.

    Ref: UPC — IAPMO

    2. The International Plumbing Code (IPC) is published by:

    1. A. IAPMO
    2. B. ICC (International Code Council)
    3. C. ASSE
    4. D. ANSI
    Show explanation

    ICC publishes the IPC as part of the International Codes (I-Codes) family, alongside the IRC, IMC, and IFGC. IAPMO publishes the UPC. Which applies depends entirely on local adoption.

    Ref: IPC — ICC

    3. A fixture trap must have a liquid (water) seal of not less than and not more than:

    1. A. 1 in and 2 in
    2. B. 2 in and 4 in (unless a deep-seal trap is specifically required/permitted)
    3. C. 3 in and 6 in
    4. D. 1/2 in and 1 in
    Show explanation

    Both codes require a trap seal of 2 in to 4 in. The seal blocks sewer gas. Deeper seals (deep-seal traps) are used where evaporation or siphonage is a concern; shallower seals are prone to being broken.

    Ref: IPC 1002.4 · UPC 1008

    4. The maximum water consumption of a tank-type water closet is:

    1. A. 3.5 gpf
    2. B. 2.5 gpf
    3. C. 1.6 gallons per flush (gpf)
    4. D. 1.0 gpf
    Show explanation

    Federal law (EPAct 1992, referenced by both codes) caps water closets at 1.6 gpf. Many jurisdictions (e.g., California) require 1.28 gpf "high-efficiency" closets via amendment — a place where state overlays tighten the model value.

    Ref: IPC 604.4 · UPC 411 / EPAct

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    Frequently asked

    What is the difference between IPC and UPC?

    IPC is published by ICC (part of the I-Codes family); UPC is published by IAPMO. Both cover the same scope but diverge on specific values — DFU tables, vent rules, AAV acceptance, etc.

    Which states use IPC vs UPC?

    Adoption is roughly geographic — the West Coast and parts of the Mountain West lean UPC, while the rest of the country tends toward IPC. See the state landing pages for exact adoption.

    Are air-admittance valves (AAVs) allowed in both codes?

    AAVs are explicitly permitted by the IPC under §917. The UPC historically prohibits them in most applications, with some jurisdiction-by-jurisdiction exceptions.