# OS MasterMap Water Network Layer Getting Started Guide
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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 digital representation of the watercourses in Great Britain as a series of connected features. The data represents the approximate central alignment of watercourses and is attributed to provide a range of information about the section of watercourses they represent.
The product has two core feature types:
* **WatercourseLink:** A WatercourseLink 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 product](https://docs.os.uk/os-downloads/products/maps-and-imagery-portfolio/os-mastermap-topography-layer).
* **HydroNode:** A HydroNode feature explicitly represents the start, junctions and end of each watercourse, as well as places where there's a change in the real-world-related attribution.
Example extract from OS MasterMap Water Network Layer showing WatercourseLink and HydroNode features.
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This Getting Started Guide focusses solely on using the product in Geography Markup Language (GML) format.
For guidance on using the product in GeoPackage or vector tiles formats, please see either the [Getting Started with GeoPackage guide](https://docs.os.uk/os-downloads/resources/product-resources/getting-started-with-geopackage-and-vector-tiles-guides/getting-started-with-geopackage) or the [Getting Started with Vector Tiles guide](https://docs.os.uk/os-downloads/resources/product-resources/getting-started-with-geopackage-and-vector-tiles-guides/getting-started-with-vector-tiles).
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## Index
This guide includes the following sections:
* [Requirements for using the data](https://docs.os.uk/os-downloads/resources/product-resources/end-of-life-product-documentation/os-mastermap-water-network-layer/os-mastermap-water-network-layer-getting-started-guide/requirements-for-using-the-data)
* [Structure of the supplied data](https://docs.os.uk/os-downloads/resources/product-resources/end-of-life-product-documentation/os-mastermap-water-network-layer/os-mastermap-water-network-layer-getting-started-guide/structure-of-the-supplied-data)
* [Loading GML data into a GIS](https://docs.os.uk/os-downloads/resources/product-resources/end-of-life-product-documentation/os-mastermap-water-network-layer/os-mastermap-water-network-layer-getting-started-guide/loading-gml-data-into-a-gis)
* [Creating a water network using ESRI software](https://docs.os.uk/os-downloads/resources/product-resources/end-of-life-product-documentation/os-mastermap-water-network-layer/os-mastermap-water-network-layer-getting-started-guide/creating-a-water-network-using-esri-software)
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