Wessex Water has agreed a pioneering new trial for permits at sewage treatment works with the Environment Agency.

The Bristol Avon catchment-wide permitting trial has been officially signed off, prompted by the need to reduce levels of phosphorus being discharged from sewage works into the River Avon to meet the requirements of the Water Framework Directive.

A traditional individual site permitting approach would have meant expensive capital investment at all 24 sewage works where reduced phosphorus levels are required. The trial is aiming to achieve these environmental improvements at a lower overall cost.

The utility said that by working with the Environment Agency to develop the catchment permit it will be minimising the risk of failing to meet the new tighter discharge standards - and therefore better placed to meet the environmental objectives in the Bristol Avon - but with less upfront investment.

"This new approach helps to ensure we continue to enhance standards in the environment but at an overall lower cost to our customers," said director of regulation and customer services Andy Pymer.

"The Bristol Avon is an important river catchment for Wessex Water where, in addition to catchment permitting, we are actively working with many partners on other major influences within the catchment to reduce the level of phosphorus in the river system as part of a wider catchment-based approach."

Nick Gupta, the Environment Agency's Wessex area manager, said:

"We are keen to promote innovation and this is great example of a company taking the initiative.

"At its heart is the desire to achieve the best environmental outcomes while managing the risks of breaking new ground. Getting to this point has been very much a collaborative process with a strong sense of common purpose.

The catchment permitting trial will begin in earnest on 1 January 2017 and will run for four years. If successful, it is anticipated that the approach will be adopted more widely in the west country and across the UK.