OS Water Network
OS Water Network is a top-quality dataset, generated from Ordnance Survey's National Geographic Database (NGD). For anyone needing detail of Great Britain’s water networks, OS Water Network ensures accuracy, detailed attribution, and improved data management options.
With new features such as unified geometries for named watercourses and expanded formats, OS Water Network supports advanced analysis in environmental management, flooding prediction, and more. It’s also replacing OS MasterMap Water Network Layer as of 31 March 2026 – we recommend migrating to OS Water Network as soon as possible, to ensure continuity.
For migration assistance or questions, email hello-geo@idoxgroup.com
Why choose Emapsite for OS Water Network?
At Emapsite, we understand there’s more to an update than ‘new data’. Making the transition to OS Water Network means you’ll have access to more detail, more value, and a wider range of choices for your business. Our experts want to help you maximise those opportunities.
With our platform, you’ll get seamless access to OS Water Network, empowering your projects in risk assessment, environmental stewardship, and infrastructure planning – but you’ll also get access to our teams, too. For more details, custom quotes, or demos – do contact us.
Email hello-geo@idoxgroup.com
What can OS Water Network do for me?
OS Water Network offers one of the world’s most detailed, three-dimensional water networks, representing the flow and precise course of every river, stream, lake, loch, drain, and canal in Great Britain as a connected link-and-node network.
Derived from the OS NGD, it provides a detailed centre line following the curve of the waterway precisely, including coordinates of watercourse sources and where they meet.
Key Features of OS Water Network
Rich Attribution: Includes width, gradient, flow direction, water type (inland or tidal), physical containment (e.g., culverts, tunnels), and more for water network links.
Named Waterways: Identified through Water Link Sets, which provide a single geometry for complete named watercourses, simplifying analysis of entire rivers or streams.
Advanced Filtering and Selection: Use attributes such as description, catchment name, and ID to filter and select data efficiently.
Enhanced Data Model: Features like Water Links (formerly Watercourse Links) and Water Nodes (formerly Hydro Nodes), with additional details on permanence, provenance, and lifecycle metadata.
Quarterly Updates: Data is refreshed every three months (January, April, July, October) to ensure accuracy and relevance.
National Coverage: Comprehensive across Great Britain, with improved width calculations and greater detail for hydrological modelling.
Compared to the OS MasterMap Water Network Layer, OS Water Network introduces enhancements such as more granular classifications (e.g., drains, overflows), separated provenance sources, and simplified attribute names for easier querying.
Why should I choose OS Water Network?
Benefits
Environmental and Ecological Insights: OS Water Network supports species migration studies, upstream pollution monitoring, ecology assessments, and the management of statutory directives like the Water Framework Directive.
Flooding and Disaster Management: OS Water Network will help you to optimize predictive models for flood protection, response measures, and assessing the impacts of natural disasters.
Planning and Engineering: With OS Water Network, you’ll enable detailed 2D and 3D modelling with precise heights in relation to sea level, flow directions, gradients, lengths, and widths — ideal for planners, surveyors, and engineers.
Waterway Management: OS Water Network facilitates better oversight of rivers and canals, including environmental impact evaluations and waterway optimization.
Migration Advantages: Users transitioning from OS MasterMap will benefit from backward-compatible TOIDs (retained as an attribute until 31 March 2026), new OSIDs for unique identifiers, and flexible data supply options that reduce processing time and data volume.
OS Water Networks – Technical Data
Data Structure: Vector - topologically structured link and node network.
Attributes: Watercourse name (with language alternatives and hierarchies), flow direction, gradient, primary flow, permanence, water type, physical containment, catchment name and ID, lifecycle metadata (e.g., change type, version date), and measurements like average width.
Scale: 1:1250 – 1:10 000.
Update Frequency: Quarterly.
Coverage: National (Great Britain).
Unique Identifiers: Primarily uses OSIDs (UUIDs) for features and nodes, with TOIDs available for legacy compatibility.
Data Access: Available via download and API, with options for true area-of-interest selections, Change-Only Updates (COU), and attribute-based filtering.
Data Formats and Supply Options: OS Water Network can be supplied in CSV or GeoPackage formats.
Unrivalled resources
We simplify the supply and management of mapping products, plans and reports. Blending diverse datasets to uncover hidden commercial insights.
Business intelligence
Our spatial intelligence enables our clients to pinpoint areas of risk and reward, and to make better business decisions faster.
Proven partnership
We work in partnership, we're supportive, and we're committed to reducing our own and our clients' impact on the environment.