
United Utilities: Petteril Project
Cost-efficient water quality improvements benefitting customers and nature.
What we know
In 2015, United Utilities set out to improve water quality in the River Petteril, which begins at Motherby near Penrith and flows north through farmland and rural communities until it joins the River Eden in Carlisle.
The main issue in the catchment was the level of phosphorus in the water course which was exceeding levels set out in the Water Framework Directive.
Initially several tiny rural wastewater treatment works were identified for upgrades to chemical treatment however this was disproportionately expensive compared with the number of customers served and not very sustainable. It was identified that farming in the area contributed to a significant amount of farm runoff reaching the river and increasing phosphorus levels.
Flood risk in the catchment and downstream in Carlisle was also a consideration. The traditional approach to improving river quality by treatment work did not factor in these issues, and did not allow for holistic, systems-based solution to the problem.

What we’re doing
United Utilities’ approach was bold and ambitious.
It worked with a variety of organisations including the Environment Agency and the agriculture industry in the area to lower levels of phosphorus. And it sought to achieve its aim with fewer engineering solutions and less money spent.
The company worked with the local Rivers Trust and farmers to understand management of phosphorus in the area in order to calculate and agree a target for phosphorus reduction with the Environment Agency. The local Rivers Trust then worked with the agricultural sector to identify and deliver farm improvements to reduce phosphorus pollution.
A combined approach between working with farmers and delivering upgraded treatment works involving intensive chemical dosing solutions helped to lower the phosphorus levels.
The solution included creating ponds to help capture and filter water, as well as investing in farmyard improvements to prevent water getting into slurry stores.



What it’s worth
The Petteril project achieved and exceeded its target reduction in phosphorus levels in the river through a powerful collaborative approach with farmers and other stakeholders.
The improvements made were achieved cost-efficiently, representing value for customers—more than £7 million was saved in comparison to the traditional engineering-based solution.
The partnerships created have also laid down the roots for further collaborative working and an integrated approach to managing pollution in the catchment into the future. United Utilities is now actively engaged in aligning interests with other partners to create a catchment market for nutrient reduction and deliver further reductions to phosphorus levels.