How Polluted Are London's Rivers? The Watershed Map Gives Some Answers

By M@

Last Updated 09 July 2024

How Polluted Are London's Rivers? The Watershed Map Gives Some Answers
A coot on polluted water with map of pollution underneath
Background image: Matt Brown

Find out potential sources of water pollution near you.

The spoliation of Britain's rivers is never far from the news. The headlines usually focus on the dumping of sewage into major rivers like the Thames. But there are many other potential sources of enfoulment to keep an eye on.

Watershed's pollution map is a rather brilliant tool that helps us do just that. The map covers the whole of Great Britain, with some data for Ireland and Northern Ireland. It shows the measured water quality in many minor rivers, as well as potential sources of pollution such as landfill, contaminated land and areas of intensive farming. The map can also be tweaked to show things like local flood risks, as can be seen in this wider-London view.

Flood risks

In these maps, the purple patches are permitted landfill sites while yellow shows historic landfill sites. Click on any of these (not here, but on the Watershed website) and you can find more details about each one.

Here's the land around Heathrow, for example. It's almost a full halo of contaminated land.

Water quality in London seems to be 'moderate' across most rivers and canals. One exception is the River Lea, which is shown in red for much of its London run, indicating 'bad' water quality.

There are many other intriguing details you can dig into. For example, the water quality in the Men's Pond on Hampstead Heath is deemed 'excellent', while the Ladies' Pond is merely 'good'.

Watershed is a not-for-profit organisation that uses investigative journalism to find out who is polluting the country's water. It aims to "hold the powerful to account, uncover abuses, illuminate overlooked stories, and champion solutions".

Their pollution map consolidates the reams of data they've accumulated over the course of those investigations — more than 120 combined datasets. These don't show causation or correlation — the presence of a landfill site does not automatically mean nearby rivers will be more polluted, for example — but the map is intended as a jumping off point for people to ask questions:

As journalists, the temptation is to hoard information until you’re ready to break a big story but nature in the UK is in crisis so we decided to to arm as many people as possible — other journalists, campaigners, communities, scientists, policymakers, regulators, lawyers and more — with as much open source data as we can.

And the map is regularly updated. A new layer lets you see precisely which parliamentary constituency a watercourse or potential pollution source falls into:

Go have a play with the Watershed pollution map, and see what you can discover about your local liquid.