OS MasterMap Water Network Layer
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The OS MasterMap Water Network Layer product (also referred to as OS MasterMap Networks – Water Layer) will become End of Life on 31 March 2026. As of this date, Ordnance Survey will cease to maintain or publish updates, and access to the product will be removed from the OS Data Hub, OS Features API and OS Vector Tile API.
Further information and details about the recommended product migration pathway are available on the End of Life Product Notices page.
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.
OS MasterMap Water Network Layer is fully interoperable with all existing layers of OS MasterMap, and enables a new generation of analysis, policy development and environmental reporting.
With this water network data, you can look up the height of any watercourse, along with its flow direction, gradient, length and width anywhere along its length.
As an island, water defines Great Britain. No other visualisation of our nation’s watercourses details the heights of watercourses in relation to sea level with this level of precision.
For planners, for surveyors, for engineers – this layer offers the potential to model in 2D and 3D like never before, thanks to the clarity of river flow, gradient and river widths.
From aqueducts to tunnels, with annotations of flow direction, OS MasterMap Water Network Layer provides useful detailed mapping that includes underground watercourses (inferred from entry and exits).
OS MasterMap Water Network Layer provides a detailed centre line following the curve of the waterway precisely. It includes the coordinates of watercourse sources and where they meet, exactly.
Access to this product is free for Public Sector Geospatial Agreement (PSGA) Members. Find out if you are a PSGA Member or download a sample of OS MasterMap Water Network Layer data by accessing the product page on the OS website, which has links to all of the relevant resources. Alternatively, you can try out the full product by applying for a Data Exploration license.
This product is available to try out free online using one of our three sets of sample data (Exeter, Newport and Inverness) through the OS MasterMap Product Viewer:
OS MasterMap Water Network Layer data is available from our OS Features API, providing location-based insights combining topography data with buildings, transport, and water layer data to create finely detailed datasets with a high degree of accuracy. Visit the OS API docs site to unlock programmatic access to rich geospatial data and integrate OS data and services into your applications.
Access to OS MasterMap Water Network Layer data is also available through the OS NGD Water Theme, providing a three-dimensional structured link and note network of watercourses for Great Britain. Users may find that OS NGD Water Theme data is more accessible, contains greater attribution, and is easier to use with databases and GIS software. Visit the OS NGD docs site to discover how to access the OS NGD and learn what's available to users.
To access additional documentation and resources relating to this product, please refer to the following:
