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Data Sources
Metric
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Date filter
River health (WFD)
Drag a box on the map to crop the data to that area.
Data sources & credits
This map is built from open data published by regulators, water companies and research bodies, together with readings contributed by community organisations. We are grateful to all of them.
Water quality monitoring
- Environment Agency — Water Quality Archive (England), the map's largest source, plus the Catchment Data Explorer and designated bathing water classifications.
- Natural Resources Wales — water quality and river monitoring in Wales.
- Scottish Environment Protection Agency (SEPA) — water classification and bathing waters in Scotland.
- Department of Agriculture, Environment and Rural Affairs (DAERA) — bathing waters in Northern Ireland.
Community and citizen science
- Full Circle Labs — first-party field sampling.
- The Wildlife Trust for Bedfordshire, Cambridgeshire & Northamptonshire — contributed catchment sampling.
- WildReach — contributed catchment sampling.
- Independent contributors who upload their own sampling data. Individuals are not named here, and personal details are never published on the map.
Storm overflows (CSOs)
Near-real-time discharge status and event duration monitoring published by the water and sewerage companies:
- Anglian Water
- Northumbrian Water
- Scottish Water
- Severn Trent Water
- South West Water
- Southern Water
- Thames Water
- United Utilities
- Welsh Water (Dŵr Cymru)
- Wessex Water
- Yorkshire Water
Rivers, catchments and rainfall
- Ordnance Survey — OS Open Rivers river network. Contains OS data © Crown copyright and database right.
- UK Centre for Ecology & Hydrology — National River Flow Archive catchment boundaries.
- Environment Agency — daily rainfall from the national gauge network.
Mapping and tools
- OpenStreetMap contributors — basemap data, © OpenStreetMap contributors, ODbL.
- CARTO — basemap tiles and styles.
- what3words — three-word addresses for sampling sites.
- Uber H3, deck.gl and MapLibre GL — hexagonal binning and rendering.
Public sector data is used under the Open Government Licence v3.0, except where stated otherwise. Readings are presented as published; any errors in aggregation or display are ours, not the providers'.
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Add a datapoint
You can search for a particular point of interest or a postcode. You can also select a different metric from the metric window to display national water quality data for Total Oxidised Nitrogen, Phosphate and E. coli.
Sampling site
Catchment
Upstream rivers
Rainfall station
Sewage outfall:
Discharging
Recently discharged
Not discharging
Each hexagon aggregates water quality samples from that area. Zooming in shows more detailed water quality data for specific sampling sites. Click a hexagon to explore.
See individual measurements alongside daily rainfall and upstream sewage discharge events, helping you understand what is driving pollution. Ideal target values for each analyte are shown and highlighted on the graph. Hovering over a sewage discharge event highlights the corresponding outfall site on the map.