Skip to content

OS MasterMap Water Network Layer

OS MasterMap® Water Network Layer offers one of the world’s most detailed, heighted water networks, showing the flow and precise course of every river, stream, lake and canal in Great Britain.

From aqueducts to tunnels, with annotations of flow direction, OS MasterMap Water Network Layer provides the detailed mapping that’s most useful – including underground watercourses (inferred from entry and exits).

Proximity is key. Organisations can understand water-related risks in detail, combining OS MasterMap Water Layer with OS MasterMap Topography Layer, property information and 3D height data for even richer insights.

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.

Answers on tap

Answers on tap

With this water network data, you can look up the height of any water course, along with its flow direction, gradient, length and width anywhere along its length.

How far, how wide

How far, how wide

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.

Content and context

Content and context

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.


Technical specification
Key FeaturesWhat this product offers
FormatGML 3.2
Data structureVector - topologically structured link and node network
AttributesWatercourse name, flow direction, gradient, primary flow, TOID® reference, EA or SEPA catchment name and ID
Scale1:1250 – 1:10 000
Update frequencyQuarterly - April, July, October, January
SupplyDVD and download


OS MasterMap Water Network Layer is available under the following licences:

Explore our data

You’re welcome to try out this data for free under our Data Exploration Licence.

Internal business use

When using OS data in your own business, you need our Framework Contract (Direct Customers) together with a data contract.

Creating products or services

To use this data commercially in your own products and services, or to distribute it, you will need to sign up to our Framework Contract (Partners) and a relevant defined use contract. This will vary depending on what you’re going to do with the data.

How to get this product

Sample data

Give it a try

Download a small area of OS MasterMap Water Network Layer sample data.

Or you can apply for a Data Exploration Licence to try out the real thing.

OS MasterMap Water Network Layer FAQs

Case studies

GIS improves Wiltshire flood management

Wiltshire have combined local knowledge with Ordnance Survey mapping to analyse local flood impacts and risks in Dauntsey Parish.