# Gridded Water Distribution System: Building Code Definition > How the IRC 2009, IPC 2009 define gridded water distribution system, where the wording differs, and which chapters depend on the term. - Canonical: https://harth.build/resources/glossary/gridded-water-distribution-system/ - Last updated: 2026-09-07 - Data source: 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. ## Key facts | Fact | Value | | --- | --- | | Defined in | IRC 2009, IPC 2009 (2009 editions transcribed in this corpus) | | Primary source | IRC 2009 Definitions (model text, not a jurisdiction's adopted text) | | Chapters using the term | 2 (counted across the codes hosted here) | | Wording identical across codes | Yes (compare before citing one code's wording under another) | ## Direct answer Gridded water distribution system is a defined term in the International Residential Code (IRC) 2009, in Definitions. The code's own words are: “A water distribution system where every water distribution pipe is interconnected so as to provide two or more paths to each fixture supply pipe.” The IPC 2009 carries the same definition word for word, so the term means the same thing in each. The term is used in 2 chapters of this corpus, most often in Definitions (IPC 2009), Definitions (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](https://nz.linkedin.com/in/barrington), Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.* ## What does this term mean? **Gridded Water Distribution System** — IRC 2009, Definitions: > A water distribution system where every water distribution pipe is interconnected so as to provide two or more paths to each fixture supply pipe. ![Labeled code-term definition diagram: Gridded Water Distribution System: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/gridded-water-distribution-system/diagram-1344.webp) *How the IRC 2009, IPC 2009 define gridded water distribution system, where the wording differs, and which chapters depend on the term.* ## What must be verified before using this guidance? Two of the I-Codes in this corpus define **Gridded Water Distribution System**, in identical words. | Code | Where it is defined | Definition | | --- | --- | --- | | IRC 2009 | [Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/definitions.md) | A water distribution system where every water distribution pipe is interconnected so as to provide two or more paths to each fixture supply pipe. | | IPC 2009 | [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/definitions.md) | A water distribution system where every water distribution pipe is interconnected so as to provide two or more paths to each fixture supply pipe. | ## Where gridded water distribution system is used in the code The term appears in 2 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next. | Chapter | Code | Mentions | | --- | --- | --- | | [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/definitions.md) | IPC 2009 | 1 | | [Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/definitions.md) | IRC 2009 | 1 | ## The terms gridded water distribution system is built out of The definition above leans on 2 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what gridded water distribution system covers: - **[Fixture Supply](https://harth.build/resources/glossary/fixture-supply.md)** — IRC 2009: The water-supply pipe connecting a fixture or fixture fitting to a fixture branch. - **[System](https://harth.build/resources/glossary/system.md)** — IFC 2009: An assembly of equipment consisting of a tank, container or containers, appurtenances, pumps, compressors and connecting piping. ## Gridded Water Distribution System: what to open, and in what order Every row is a document this term depends on. The [ICC code library](https://codes.iccsafe.org/codes) and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) cover the middle rows. | Check | Where | Confirmed | | --- | --- | --- | | Read the definition in the adopted IRC | Definitions | | | Read the definition in the adopted IPC | Definitions | | | Re-check the requirement that uses it | Definitions (IPC 2009) | | | Re-check the requirement that uses it | Definitions (IRC 2009) | | | Confirm the dependent definition | Fixture Supply | | | Confirm the dependent definition | System | | | 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. ## Where can you explore related guidance? - [Explore all glossary guidance](https://harth.build/resources/glossary.md) - [Fixture Supply: Building Code Definition](https://harth.build/resources/glossary/fixture-supply.md) - [System: Building Code Definition](https://harth.build/resources/glossary/system.md) ## 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](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. ### Source links - [codes.iccsafe.org](https://codes.iccsafe.org/codes) - [iccsafe.org](https://www.iccsafe.org/advocacy/code-adoption-maps/) ## Frequently asked questions ### What is the code definition of gridded water distribution system? The International Residential Code (IRC) 2009 defines it in Definitions as: “A water distribution system where every water distribution pipe is interconnected so as to provide two or more paths to each fixture supply pipe.” 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 gridded water distribution system? In this corpus the term is used across 2 chapters, led by Definitions 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. --- - Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Fgridded-water-distribution-system%2F - View this page in a browser: https://harth.build/resources/glossary/gridded-water-distribution-system/ - All resources for agents: https://harth.build/llms.txt