Bring back clean water to bring back freshwater life
10th March 2026
Restoring clean water to our landscapes is fundamental to reversing freshwater biodiversity loss, says Freshwater Habitats Trust and Newt Conservation Partnership Technical Director Pete Case.
Clean water is the foundation of life in freshwater but it has become an increasingly scarce resource. Without it, we have no hope of reversing the catastrophic declines in freshwater biodiversity.
Restoring clean, unpolluted water to our towns and countryside may be the single most important thing we can do for freshwater wildlife. That’s why bringing back clean water is one of the four principles we’re using to build the Freshwater Network.
What is clean water and why does it matter?
When we talk about ‘clean water’, we mean water that is close to its natural chemical condition: low in nutrients such as phosphates and nitrates, free from toxic pollutants like heavy metals, and able to fully support natural ecological processes. These are the conditions in which freshwater plants and animals evolved – and the conditions they still need today.
Sewage pollution in rivers is often at the forefront of people’s minds when we raise the issue of freshwater pollution. But pollution comes from many sources, and it does not just affect large rivers and lakes. Small waters such as ponds, headwater streams, springs, and flushes are some of the most important freshwater habitats for biodiversity, yet they are also the least well-protected and the most vulnerable to nutrient enrichment.
- Clean water testing in the Ock catchment.
Diffuse nutrient pollution from agriculture, urban runoff, sewage inputs and road drainage now affects almost every freshwater catchment in the UK. Even low-level pollution can have profound ecological effects.
Clean water habitats have become increasingly rare, and with them, the species that depend on them. The consequences for biodiversity are profound: rare aquatic plants, specialist invertebrates, and amphibians that depend on high-quality habitats are disappearing from landscapes where they once thrived.
As nutrient levels rise, fast-growing and more pollution-tolerant plants and algae take over, out-competing sensitive species for resources. The result is a rapid decline in species diversity. This process is playing out across our rivers, lakes, ponds, ditches and wetlands as habitat fundamentally changes as a response to nutrient enrichment.
The evidence: clean water creates biodiversity hotspots
Our Clean Water for Wildlife surveys, show just what a scarce resource clean water is across the freshwater environment. A survey of habitats including ponds, lakes, ditches, streams, and rivers in the Greater London area found that 60% were highly polluted and a further 10% showed some evidence of nutrient pollution. Perhaps more surprisingly, a similar survey carried out in the Ock catchment – a rural area in Oxfordshire – revealed that only a quarter of habitats showed no evidence of nutrient pollution. We continue to observe similar results across our project work.
The most encouraging finding from our research, however, is that freshwater wildlife can recover quickly when clean water is available. That means we know we can rapidly reverse the decline in freshwater biodiversity by creating new clean water habitats.
The 2025 NatureSpace Licensing schemes monitoring results report is the most recent research to illustrate this point. Ninety percent of mature sites where the Newt Conservation Partnership has created or restored clean water ponds are now occupied by Great Crested Newts. The scheme is also having a transformative effect on the wider landscape, enhancing freshwater biodiversity by boosting populations of rare and threatened species – including, most notably in the last year, Pondweed Leafhopper and Clustered Stonewort.
The key to the success of the scheme is not only in the design of the ponds, but in the carefully chosen locations, ensuring they connect with existing newt habitats – and, crucially, remain unpolluted.
- Great Crested Newt (Alamy - Jack Perks)
Research we’ve carried out in a typical agricultural landscape, the Water Friendly Farming demonstration site in Leicestershire, has clearly shown that the creation of new clean water ponds can dramatically increase freshwater biodiversity in a relatively short space of time. Our research paper published in 2020 described how this work increased wetland plant by more than a quarter (26%) and trebled the number of regionally rare plant species.
Similar results have been achieved with our Pitsford Water Friendly Farming project in Northamptonshire. Working with Anglian Water and local landowners in the Pitsford reservoir catchment, we increased the number of wetland plant species across the whole landscape by nearly a quarter and more than doubled the number of uncommon plant species in just two years simply by creating clean water ponds.
This isn’t just about ponds. Clean headwater streams, unpolluted springs and flushes, and well-managed fens all demonstrate the same principle: where clean water flows, biodiversity flourishes. These small waters are particularly important because they can act as refuges, and as sources from which species can spread across the landscape as we extend the network of high-quality freshwater habitats.
- Headwater stream in the New Forest
Putting evidence into practice
Bringing back clean water isn’t just an aspiration, it’s something we’ve been actively doing for decades across England and Wales. And our research gives us the evidence to drive our practical conservation work and ensure it will make a difference.
For the Newt Conservation Partnership, we recently dug our 500th pond. This was a significant milestone and a proud moment for a team that’s been dedicated to creating and restoring clean water ponds for seven years.
The pond design expertise we bring to this work comes from nearly four decades of experience. Back in 1990, we started work with the Environment Agency and Thames Water on a major new pond complex at Pinkhill Meadow near Oxford to trial new ideas about river floodplain restoration. The site features waterbodies of different sizes, depths, permanence and water source to achieve maximum diversity. Crucially, all are unpolluted, despite being so close to the River Thames.
Thirty-five years on and Pinkhill is recognised as an Important Freshwater Area because of its high number of Priority Ponds and because it supports 20% of Britain’s wetland and freshwater plant species.
We’re building on this success in Oxfordshire with our Landscape Recovery project, where we’re collaborating with River Thame Conservation Trust, landowners and other partners to restore the freshwater landscape across the Ock and Thame catchments. The focus is on bringing back clean water on farmland with low productivity, to boost biodiversity without impacting on farm businesses.
- A pond created by Freshwater Habitats Trust and partners at Pinkhill Meadow, Oxford
And in mid-Wales we’re working with farmers, landowners and the local community to protect and restore the River Irfon catchment. A Special Area of Conservation, designated for its exceptional freshwater biodiversity, the Irfon supports one of the few remaining UK populations of the Freshwater Pearl Mussel – a species that relies on pristine water. However, water quality in the catchment is declining.
Alongside creating new clean water ponds and scrapes, we’re partnering with farmers and landowners to reduce pollution and sedimentation in existing waterbodies. Crucially, this work does not focus solely on the main river channel, but on the whole freshwater environment, including streams, ponds and wetlands.
From practice to policy
To carry out this practical work at a big enough scale to reverse the long decline of freshwater wildlife, we need better policy.
The forthcoming Water Reform Bill represents a critical opportunity to reset how water is managed in England. More ambition for our highest quality waterbodies, and meaningful monitoring of the whole water environment are both essential if we are to halt freshwater decline.
The Headstart initiative, which we’re developing with Anglian Water and other partners, is an example of how we could combine evidence from scientific research with practical conservation work to bring about systematic change. Headstart will demonstrate the benefits of headwater catchment restoration and build the case for wider investment by the water industry – harnessing the power of headwater habitats to bring back clean water.
Clean water for a brighter future
Bringing back clean water means rethinking where we invest, what we protect, and how we design freshwater landscapes. And it means recognising that unpolluted water is the lifeblood of our freshwater ecosystems and committing to restoring it.
Our work proves that when we bring back clean water, nature responds. As we build the Freshwater Network the challenge is to scale up so we can move from individual sites and projects to landscape-scale transformation.
Without clean water, even our best-protected sites will continue to decline, and our efforts to create new habitats and connect landscapes will fail. But with clean water flowing once more, our ponds, streams, and wetlands, give freshwater biodiversity a genuine chance to recover.
The principle is simple: bring back clean water and bring back freshwater life.
- A freshwater landscape in the Irfon catchment - Jason Elberts