About FloodRadar — Why we built it, after the water came in

We were flooded. So we set out to understand why.

FloodRadar began after the water came in — and the questions that wouldn't leave afterwards. It's our attempt to understand how rainfall and the rivers upstream become the flood at your door, and to share what the data quietly shows.

The water arrives fast. The questions stay for years.

If you've been flooded, you don't need it described. The water comes up through the floor and the doorways at once. Then come the months that nobody photographs — the drying, the stripping-out, the forms, the smell, and the small lurch in your stomach every single time it starts to rain.

When the worst of it had passed, we were left with one question we couldn't answer: why here, and why then? The rain that flooded us had mostly fallen somewhere else — on hills miles upstream, hours earlier. The river had simply carried it to our door. It felt like something that should have been seeable coming.

So instead of just bracing for the next one, we started reading. The Environment Agency publishes a remarkable amount of open data — thousands of river gauges, rainfall records, flood histories. We taught ourselves to read the river, and FloodRadar is what we built to make that legible for everyone else, too.

We couldn't stop the next flood. But we could refuse to be surprised by it.

How a flood actually reaches you

A river flood is rarely about the rain outside your window. It's a chain of events that usually starts upstream and hours earlier — which is exactly why it can be watched.

Rain falls on the hills

Often miles from you, often the day before. The rainfall gauges upstream feel it first.

The catchment fills up

Already-soaked ground stops absorbing; the rest runs off into streams and tributaries across the catchment.

A wave travels downstream

That water gathers and moves toward you at the river's own pace — a flood wave we can track between gauges.

Your river rises

Levels climb past their normal range. Our rising-now view and predictions try to read this early.

And then it overtops

The river leaves its channel and the water arrives. By now the official flood warnings are the thing that matters most.

We watch the official warnings — and try to warn you sooner

We don't issue the official warnings — those belong to the Environment Agency. What we try to add is a head start: watching every alert they raise, reading what's happening upstream, and folding in every other signal we can find.

We watch the official warnings

Every Environment Agency flood alert and warning, surfaced the moment it's raised — so the official picture is always one tap away.

We try to warn you earlier

Our own alerts look upstream and use machine learning to flag rising risk before it reaches you. It's not an exact science yet — flooding rarely is — but we sharpen it with every event.

We watch more than the river

Beyond levels we track rainfall and nearby storm-sewage discharges — the things that shape how a flood actually plays out on the ground, not just whether a river is high.

We're joining the dots

We're pulling in new data across many fields — river flow, groundwater, soil moisture, weather forecasts — to make our warnings earlier and clearer, especially as the climate keeps moving the goalposts.

We are a companion to the official warnings, never a replacement.

FloodRadar is not a substitute for the Environment Agency. Their flood warnings and alerts are the official, authoritative source, and they always take precedence. Please sign up for them, and act on them.

What we add is a second pair of eyes and a longer memory: we keep watch on those official alerts, and we analyse the Environment Agency's open datasets to bring meaningful insight — especially as a changing climate reshapes what "normal" looks like for a river. Treat anything here as context and early thinking, not as instruction.

⚠ If there is an immediate risk to life, call 999.