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Anglian Water

Ingoldisthorpe Project, an innovative approach to water treatment.

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  • What we know
  • What we’re doing
  • What it’s worth
  • Testimonial

What we know

Anglian Water’s wetland treatment site at Ingoldisthorpe in Norfolk, created in partnership with the Norfolk River’s Trust, is the first of its kind in England.

Ingoldisthorpe Water Recycling Centre is a medium-sized work serving villages in west Norfolk such as Ingoldisthorpe, Snettisham and Dersingham. In dry weather conditions, it discharges 1400m3 of treated water each day into the River Ingol, a 10km-long chalk stream that drains into the sea west of Dersingham.  The Environment Agency urged Anglian to remove more ammonia and phosphorus from the effluent.

The standard for ammonia was set at 1mg/l in addition to a new total phosphorus limit of 4.5mg/l. To meet this challenging target, new technology – a Membrane Bioreactor (MBR) – was needed. However, this solution was high cost and not as tried and tested as other technology. The cheaper and simpler alternative was to pump the effluent away to another Water Recycling Centre, but this risked significantly reducing the Ingol’s flow.

Small waterfall

What we’re doing

During discussions with the Environment Agency, a novel solution was agreed.

The company would install a Nitrifying Sand Filter at the works to achieve an ammonia level of 3mg/l. As well as that, a wetland designed to further improve water quality would be constructed. Together, the Nitrifying Sand Filter and wetland would meet the new ammonia standard and potentially further reduce total phosphorus concentrations discharged back to the river Ingol.

The wetland is a series of four interconnected shallow ponds through which water from the Water Recycling Centre flows. The ponds are planted with species suitable for the location and habitat such as water mint, water avens, marsh marigold and flag iris. Water filtering throughout is improving in quality before discharging into the Ingol. Norfolk Rivers Trust secured a lease to operate the wetland for the next twenty years.

Anglian water workers
Run off water in forest

What it’s worth

The Ingoldisthorpe treatment wetland, in place since spring 2018, has been a great showcase for the potential of a ‘natural capital approach’ to treating water —or simply put, using nature to help nature.

The wetland is enhancing biodiversity by providing new wildlife habitat of value for invertebrates, mammals and birds. It covers about one hectare of land and lies immediately downstream of the Water Recycling Centre.

Benefits to customers, Anglian Water and construction partners include reduced cost, reduced carbon, and increased natural capital. Benefits to Norfolk Rivers Trust include: funds to build and operate the wetland, and opportunity to develop more organisational experience and expertise in treatment wetlands.

Benefits to the Environment Agency include: regulatory requirements met, an innovative proof-of-concept solution that can now be implemented elsewhere, enhanced beauty, heritage and engagement with the natural environment


Peter Simpson

Our treatment wetland at Ingoldisthorpe shows how we can harness nature-based solutions to meet our needs and improve biodiversity, whilst reducing cost and carbon. It’s a great example of how we bring environmental and social prosperity to our region and how we can meet our net zero carbon 2030 commitment."

Peter Simpson CEO, Anglian Water Group