Updated 2026-09-07

Building Code Glossary

Flush Tank: Building Code Definition

How the IPC 2009 define flush tank, where the wording differs, and which chapters depend on the term.

On this page

Last updated September 7, 2026 · Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The [ICC code library](https://codes.iccsafe.org/codes) publishes the current model text and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) show which edition a jurisdiction has adopted; those sources control.

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Direct answer

Flush tank is a defined term in the International Plumbing Code (IPC) 2009, in Definitions. The code's own words are: “A tank designed with a fill valve and flush valve to flush the contents of the bowl or usable portion of the fixture.” No other I-Code in this corpus defines it, so the IPC 2009 definition is the one to work from. The term is used in 5 chapters of this corpus, most often in Fixtures, Faucets and Fixture Fittings (IPC 2009), Plumbing Fixtures (IRC 2009), Water Supply and Distribution (IRC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted. Record the jurisdiction, the adopted edition, the application date and any local amendment that rewrites the definition before you use it on a live project, because a term redefined by amendment changes every requirement that depends on it.

Content and cited inputs reviewed by Scott Barrington, Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.

What does this term mean?

Flush Tank — IPC 2009, Definitions:

A tank designed with a fill valve and flush valve to flush the contents of the bowl or usable portion of the fixture.

Labeled code-term definition diagram: Flush Tank: Building Code Definition — How the IPC 2009 define flush tank, where the wording differs, and which chapters depend on the term.

What must be verified before using this guidance?

Flush Tank is defined once in this corpus, in the Definitions chapter of the International Plumbing Code (IPC) 2009:

A tank designed with a fill valve and flush valve to flush the contents of the bowl or usable portion of the fixture.

Where flush tank is used in the code

The term appears in 5 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.

Chapter	Code	Mentions
Fixtures, Faucets and Fixture Fittings	IPC 2009	20
Plumbing Fixtures	IRC 2009	9
Water Supply and Distribution	IRC 2009	2
Definitions	IPC 2009	1
Definitions	IRC 2009	1

The term in use

How the code actually writes about flush tank, quoted from the 2009 text hosted here:

Each water closet, urinal, clinical sink and any plumbing fixture that depends on trap siphonage to discharge the fixture contents to the drainage system shall be provided with a flushometer valve, flushometer tank or a flush tank designed and installed to supply water in quantity and rate of flow to flush the contents of the fixture, cleanse the fixture and …

— IPC 2009 §425.1

Water closets that permit backflow of the contents of the bowl into the flush tank shall be prohibited.

— IRC 2009 §P2712.1

The terms flush tank is built out of

The definition above leans on 3 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what flush tank covers:

Flush Valve — IRC 2009: A device located at the bottom ofa flush tank that is operated to flush water closets.
Fill Valve — IPC 2009: A water supply valve, opened or closed by means of a float or similar device, utilized to supply water to a tank.
Valve — IRC 2009: A device used in piping to control the gas supply to any section of a system of piping or to an appliance.

Flush Tank: what to open, and in what order

Every row is a document this term depends on. The ICC code library and the ICC adoption maps cover the middle rows.

Check	Where	Confirmed
Read the definition in the adopted IPC	Definitions
Re-check the requirement that uses it	Fixtures, Faucets and Fixture Fittings (IPC 2009)
Re-check the requirement that uses it	Plumbing Fixtures (IRC 2009)
Re-check the requirement that uses it	Water Supply and Distribution (IRC 2009)
Re-check the requirement that uses it	Definitions (IPC 2009)
Confirm the dependent definition	Flush Valve
Confirm the dependent definition	Fill Valve
Confirm the dependent definition	Valve
Local amendment to any of the above	Jurisdiction's amendment list

A research aid, not a code determination. The authority having jurisdiction decides which edition and which amendments apply.

Sources and method

Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The ICC code library publishes the current model text and the ICC adoption maps show which edition a jurisdiction has adopted; those sources control.

Source links

Frequently asked questions

What is the code definition of flush tank?

The International Plumbing Code (IPC) 2009 defines it in Definitions as: “A tank designed with a fill valve and flush valve to flush the contents of the bowl or usable portion of the fixture.” The 2009 model text is reproduced here; the definition that binds your project is the one in the edition your jurisdiction has adopted, as amended locally.

Which parts of the code depend on flush tank?

In this corpus the term is used across 5 chapters, led by Fixtures, Faucets and Fixture Fittings in the IPC 2009. Those are the sections whose scope moves if the definition is amended locally, so read them together with Chapter 2 rather than on their own.

What is the HSN code for a toilet flush tank?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IPC 2009 states, in Definitions: “A tank designed with a fill valve and flush valve to flush the contents of the bowl or usable portion of the fixture.” It is defined in IPC 2009. Because it is a defined term, whatever the adopted edition says it means is what every section using it means — so check Chapter 2 of that edition and any local amendment before relying on this wording.

What is a flush tank system?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IPC 2009 states, in Definitions: “A tank designed with a fill valve and flush valve to flush the contents of the bowl or usable portion of the fixture.” It is defined in IPC 2009. It is not the same as System, which the IFC 2009 defines separately as “An assembly of equipment consisting of a tank, container or containers, appurtenances, pumps, compressors and connecting piping.” Because it is a defined term, whatever the adopted edition says it means is what every section using it means — so check Chapter 2 of that edition and any local amendment before relying on this wording.

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