The Great UK WaterBlitz returns this month!
The Great UK WaterBlitz led by Earthwatch Europe is back. This month, thousands of people across the UK will be heading out to their nearest freshwater river, stream, lake or pond armed with their FreshWater Watch sampling kits to test the quality of the water.
It’s a nationwide citizen science project where volunteers all test water quality at the same time, helping to build a clearer picture of what’s really going on in our waterways. More than 3,000 testing kits have been sent out, and our incredible volunteers will be collecting data across the country between 24-27 April.
The pollution you can’t see
We all know there is a crisis facing our rivers, but water pollution often isn’t always obvious to spot. Rivers can look clean but still be heavily polluted, which is why the WaterBlitz focuses on testing for nutrients like nitrates and phosphates. These key indicators of pollution are often linked to farming and sewage. Excess nutrients can seriously damage ecosystems, even when the water looks fine.
By testing all across the UK at the same time, volunteers create a national snapshot of water quality, revealing patterns that may otherwise be easy to miss.
“Keeping track of water quality across the whole country is a real challenge. Thousands of smaller waterways go unchecked by government monitoring programmes, leaving important gaps in our understanding. Initiatives like the WaterBlitz help fill those gaps.”
– Dr Laura Bannatyne, Earthwatch Europe Research Manager
What the last WaterBlitz found
The most recent results show why this work is so important. In September 2025, nearly 6,000 citizen scientists uploaded 3,430 data points from freshwater sites across the UK.
The overall picture wasn’t good:
- 60% of datapoints showed poor water quality due to high nutrient pollution
- The Thames river basin was the worst in the UK, with 81% of nitrate and phosphate measurements at unacceptable levels
- Cambridgeshire recorded the poorest results of any county, with 91% of measurements showing poor ecological status
But it’s not all bad news! Some areas showed that good water quality is possible:
- Counties including Tyrone, Mid Glamorgan and parts of Scotland such as Argyll and Bute and Aberdeen recorded 100% good results
- In England, Northumberland performed best, with 94% of measurements indicating good ecological status
Read more: You can explore the full findings in the Great UK WaterBlitz Autumn 2025 report.
Help our waterbodies by supporting the next WaterBlitz!
We’re really pleased that Earthwatch has been selected for match funding through the Big Give’s EarthRaise campaign. Between 22–29 April, every donation will be doubled.
That funding will help run another WaterBlitz in autumn 2026, allowing more volunteers to add to existing results and build an even clearer picture of UK water quality over time.
“Keeping track of water quality across the whole country is a real challenge. Thousands of smaller waterways go unchecked by government monitoring programmes, leaving important gaps in our understanding. Initiatives like the WaterBlitz help fill those gaps. Every FreshWater Watch result contributes to a national dataset which gives scientists and researchers a clearer picture of where pollution is happening and where action is most urgently needed.”
– Dr Laura Bannatyne, Earthwatch Europe
Missed it this time? You’ll get another chance
If you missed the sign up this time, the WaterBlitz runs twice a year. You can express your interest to be the first to hear when the next event opens and take part next time in your own community.
