# OS MasterMap Water Network Layer Documentation

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#### Product has reached its End of Life (withdrawal) date

The OS MasterMap Water Network Layer product (also referred to as OS MasterMap Networks – Water Layer) reached its End of Life on **31 March 2026**. As of this date, Ordnance Survey ceased to maintain or publish updates to the product, and access to the product was removed from the OS Data Hub, OS Features API and OS Vector Tile API. 

Supporting product documentation will be removed from this site 12 months after this date, when access to existing data packages in the OS Data Hub is no longer available. Full details, including migration information and FAQs, are available on the [OS MasterMap Water Network Layer End of Life information page](https://docs.os.uk/os-downloads/resources/product-resources/end-of-life-product-documentation/os-mastermap-water-network-layer/end-of-life-notice-os-mastermap-water-network-layer).
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OS MasterMap Water Network Layer is a three-dimensional digital representation of Great Britain's watercourses. The product includes rivers, streams, lakes, lochs and canals as a series of watercourse network lines. The network lines (links) are attributed to provide a range of information about the section of watercourse they depict. OS MasterMap Water Network Layer will significantly enhance systems used to manage waterways and rivers and the flood risk they pose.

<figure><img src="https://1897589978-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcNpJpLP8RROUaWVQo5ea%2Fuploads%2FrvnOU8QihHcoa3tDOsse%2Fimage.png?alt=media&#x26;token=c3f640eb-ce25-40c6-ba03-6d5ab7e4b57d" alt="OS MasterMap Networks - Water layer map showing river networks over land"><figcaption><p>OS MasterMap Water Network Layer map.</p></figcaption></figure>

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{% tab title="Summary" %}

* **Category**: Networks
* **Data theme**: Water
* **Data structure**: Vector – Topologically structured link and node network
* **Coverage**: Great Britain
* **Scale**: 1:1 250 to 1:10 000
* **Format**: GML 3.2.1, GeoPackage, vector tiles
* **Ordering area**: All of Great Britain or customisable areas (5km² tiles)
* **Publication months**: January, April, July, October

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## Product has now been withdrawn

Please note that the January 2026 release was the final release of OS MasterMap Water Network Layer; more information about the product withdrawal timeline and the recommended product migration pathway is available from the [OS MasterMap Water Network Layer End of Life information page](https://docs.os.uk/os-downloads/resources/product-resources/end-of-life-product-documentation/os-mastermap-water-network-layer/end-of-life-notice-os-mastermap-water-network-layer).
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{% tab title="Additional Information" %}
**Feature types included**

The feature types within the product are:

* WatercourseLink: This feature represents the alignment of a watercourse. The majority have been derived from Ordnance Survey detailed topographic data, made available to customers as the OS MasterMap Topography Layer.
* HydroNode: A HydroNode feature explicitly represents the start, the junctions and the end of each watercourse, as well as places where there's a change in the real-world-related attribution.

**Spatial reference system**

The OS MasterMap Water Network is projected in the EPSG 7405 OSGB36 / British National Grid + ODN. This projection is used as it specifies that the Z value is Ordnance Datum Newlyn.
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## Other ways to access this data

<figure><img src="https://1897589978-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcNpJpLP8RROUaWVQo5ea%2Fuploads%2FGaqG5MFeNPamVC7uaHTw%2Fwaternetwork_gitbook_page.png?alt=media&#x26;token=d02285fa-f8e1-4039-a074-bb39bf4bada1" alt="A flow diagram showing a direct line from OS MasterMap Water Layer product migration path to OS NGD Water Theme – Water Network Collection" width="362"><figcaption><p>OS MasterMap Water Layer product migration path to OS NGD Water Theme – Water Network Collection</p></figcaption></figure>

We recommend you migrate to using the data in the [OS NGD Water Network Collection](https://docs.os.uk/osngd/data-structure/water/water-network) as it contains very similar data content to OS MasterMap Water Network Layer – ​see the [Comparison of Water Network Products page](https://docs.os.uk/more-than-maps/os-ngd-migration/comparison-of-water-network-products) for a full comparison of the data supply, available formats, and attribution between the two products.&#x20;

Further details on migration, including benefits to using OS NGD Water Network Collection data, FAQs and supporting documentation are available from the [OS MasterMap Water Network Layer End of Life information page.](https://docs.os.uk/os-downloads/resources/product-resources/end-of-life-product-documentation/os-mastermap-water-network-layer/end-of-life-notice-os-mastermap-water-network-layer)

## OS MasterMap Water Network Layer documentation

To access additional documentation and resources relating to this product, please refer to the following:

<table data-view="cards"><thead><tr><th></th><th></th><th></th><th data-hidden data-card-cover data-type="image">Cover image</th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><h3>OS MasterMap Water Network Layer End of Life information</h3></td><td>The End of Life information for the OS MasterMap Water Network Layer product, containing key dates, the reasoning behind the product withdrawal, product migration guidance, and FAQs.</td><td></td><td><a href="https://1897589978-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcNpJpLP8RROUaWVQo5ea%2Fuploads%2FGaqG5MFeNPamVC7uaHTw%2Fwaternetwork_gitbook_page.png?alt=media&#x26;token=d02285fa-f8e1-4039-a074-bb39bf4bada1">waternetwork_gitbook_page.png</a></td><td><a href="os-mastermap-water-network-layer/end-of-life-notice-os-mastermap-water-network-layer">end-of-life-notice-os-mastermap-water-network-layer</a></td></tr><tr><td><h3>Overview</h3></td><td>The overview introduces OS MasterMap Water Network Layer and gives context for all users – highlighting key features, providing examples of uses, and listing details such as file sizes, etc.</td><td></td><td data-object-fit="cover" data-alt="Example image showing OS MasterMap Water Network Layer product data over a background map."><a href="https://1897589978-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcNpJpLP8RROUaWVQo5ea%2Fuploads%2F0uuBdYg4IlxB3ptTMCiP%2FMasterMap-Water-Network-5.png?alt=media&#x26;token=b043504c-d8c7-4cd8-a552-77e799626fe6">MasterMap-Water-Network-5.png</a></td><td><a href="os-mastermap-water-network-layer/os-mastermap-water-network-layer-overview">os-mastermap-water-network-layer-overview</a></td></tr><tr><td><h3>Getting Started Guide</h3></td><td>The getting started guide provides instructions for using OS MasterMap Water Network Layer in different applications. Users with limited technical knowledge will be able to follow this guide.</td><td></td><td data-object-fit="cover" data-alt="Example image showing OS MasterMap Water Network Layer product data over a background map."><a href="https://1897589978-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcNpJpLP8RROUaWVQo5ea%2Fuploads%2FY6Jh7dMYdgfFt39h0rNu%2FMasterMap-Water-Network-2.png?alt=media&#x26;token=dca348b7-7a38-4274-93c5-1355437b3aa8">MasterMap-Water-Network-2.png</a></td><td><a href="os-mastermap-water-network-layer/os-mastermap-water-network-layer-getting-started-guide">os-mastermap-water-network-layer-getting-started-guide</a></td></tr><tr><td><h3>Technical Specification</h3></td><td>The technical specification provides detailed technical information about OS MasterMap Water Network Layer. It is targeted at technical users and software developers.</td><td></td><td data-object-fit="cover" data-alt="Example image showing OS MasterMap Water Network Layer product data over a background map."><a href="https://1897589978-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcNpJpLP8RROUaWVQo5ea%2Fuploads%2FqlKAdkK0alzXzbKGwrUM%2FMasterMap-Water-Network-1.png?alt=media&#x26;token=f2ba6610-d4ee-456e-abae-43639afa48f3">MasterMap-Water-Network-1.png</a></td><td><a href="os-mastermap-water-network-layer/os-mastermap-water-network-layer-technical-specification">os-mastermap-water-network-layer-technical-specification</a></td></tr><tr><td><h3>Downloads</h3></td><td>The downloads page provides links and resources to support the application of OS MasterMap Water Network Layer within your environment</td><td></td><td></td><td><a href="https://docs.os.uk/os-downloads/networks/os-mastermap-water-network-layer/os-mastermap-water-network-layer-downloads">https://docs.os.uk/os-downloads/networks/os-mastermap-water-network-layer/os-mastermap-water-network-layer-downloads</a></td></tr></tbody></table>

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New users should start with the Overview to gain high-level insight into the product. The Getting Started Guide will help you to begin using product data in different software systems. The Technical Specification contains detailed technical insights.
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