About the data and how it works

How's the Water brings together public monitoring data for rivers, beaches and lakes in Midlands, North East, North West, Scotland, Thames Valley and Yorkshire, so you can check conditions before a swim, paddle or fishing trip. For each place it shows what the storm overflow monitors upstream or nearby are reporting, the river or lake level, recent rainfall, any flood alerts and, at designated bathing waters, the official results.

It reports what the monitors say. It never says the water is safe or clean, because nobody measures that in real time.

Where the data comes from

• -Storm overflows. Northumbrian Water, Severn Trent Water, Thames Water, United Utilities and Yorkshire Water publish their event duration monitors through Stream (CC BY 4.0). Scottish Water publishes its own near real-time overflow feed, updated hourly. Each feed gives a monitor's current status and its latest spill, so the spill history here is built up from our own readings, starting from the day each monitor was first seen.
• -River and lake levels. The Environment Agency's real-time flood monitoring API in England, and SEPA's time series service in Scotland (both Open Government Licence).
• -Rainfall. Tipping bucket rain gauges from the same two services, summed from their 15 minute readings.
• -Flood alerts and warnings. The Environment Agency's flood warning service, shown in its own words. Scottish flood warnings are not shown yet.
• -Bathing waters. The Environment Agency's bathing water register for England: yearly classifications, sample results and, in season, daily pollution risk forecasts. In Scotland, classifications from SEPA's bathing water map service, with a link to each site's results page on SEPA's site.
• -Rivers and maps. River centrelines from Ordnance Survey's OS Open Rivers, and map tiles from OpenStreetMap.

How often it updates

Overflows, river levels, rainfall and flood warnings are read every 15 minutes, and the pages are rebuilt straight after. Bathing water records are read every hour. Every page shows when its monitor data was last updated, and says so plainly when a feed has not updated for over six hours, so old figures are never shown as current.

How a place's figures are worked out

• -Upstream. For a river spot, every overflow monitor whose discharge flows past it: those higher up the same river, plus everything on the tributaries and rivers that join above it. Distances follow the water, measured along the river centreline.
• -Nearby. The sea and lakes have no upstream, so beaches and lakes list every overflow monitor within 3 km in a straight line. Overflows further away, or up rivers that flow in, can still affect the water.
• -Discharging now, spills and offline. A spill is one period an overflow released untreated sewage mixed with rainwater. A monitor that is not reporting counts as offline, never as "no spills", and a place whose monitors are all offline says so.
• -Level and rainfall. Each spot uses the nearest level gauge within 25 km along its river, and the nearest rain gauge within 20 km. The typical range is the band the gauge usually sits in, as published by the Environment Agency or SEPA.
• -Flood warnings. Shown for a spot when a warning area naming its river comes within 1 km of it.

What it does not do

• -It does not say whether water is safe or clean.
• -It does not know about spills from monitors that are offline, or from anything the water companies do not monitor.
• -It does not validate the data. The feeds are near real-time and unchecked, and the agencies and water companies may correct them later.

Who runs it

How's the Water is an independent site built by Chris Chrisostomou in Leeds. It is not connected to any water company or agency. Seen a mistake, or want a river added? Let us know on GitHub. The terms of use cover reusing the data.