Children, parents, and grandparents have been getting their hands dirty to clean up a Norfolk river heavily polluted by sewage.

Nearly 20 volunteers pitched in on the project, funded by the Norfolk Rivers Trust, to increase the biodiversity of the river.

Three lagoons were dug out close to Templewood house in Northrepps, near Cromer, and filled with native plants. The plants will purify treated sewage bound for the five-mile long River Mun.

It is the first time this water purification method has been used by a community group in England and Wales.

The project is an extension of the River Mun Community Nature Reserve.

According to Eddie Anderson, who lives at Templewood and owns the first mile of the river which is the focus of the reserve, the lagoons will be open to the public.

Mr Anderson, former ITV producer, said: 'We want to improve the biodiversity of the river and get back to the native plants and species.

'This is a grand extension of the idea to improve the river quality.

'The interest in the nature reserve plan has been absolutely phenomenal. People were horrified about the condition of the river.'

The large lagoons were dug out of unploughed meadow and the work has already improved biodiversity in the area.

Volunteers planted between 15 and 20 different native plants.

Previously, the treated effluent with high levels of phosphorus, from Northrepps sewage plant near Templewood, ran straight into the River Mun, Norfolk's second shortest river.

That caused algae growth, stopped delicate plants from growing and decreased the water quality, causing a knock-on impact for animals.

Plants in the new wetland area will absorb the phosphorus in the liquid from Northrepps before it enters the river.

Experts will monitor the system for three years and a further two lagoons will be created.

Jonathan Lewis, catchment planning officer for Norfolk Rivers Trust, said: 'This is a really important project for the trust. It is the first of its kind in England and Wales.

'The trust is looking at water quality, and for this big issue we have to look at the root cause. We are using something natural to tackle the problem.

'It is really exciting that we are getting this done in Norfolk. If it works here it can be done in other areas. We are leading the way in this process.

'We need to find solutions to water quality because our rivers are suffering.'

He added this method was an economical way to reduce phosphates in rivers.

The River Mun runs between Northrepps and Mundesley.

Nature reserve volunteers are creating a 12-acre wet woodland area to improve the space for the public.

Rob McInnes, a wetlands specialist, said the work will create benefits for the whole of the River Mun.

He said: 'Human society depends on things like rivers and wetlands. They are important for wildlife.'

• To volunteer email jonathan@norfolkriverstrust.org

• Do you have a nature story? Email sophie.wyllie@archant.co.uk