The contractor admitted a single incident of discharging silt-laden water into a tributary of the River Rother in Burwash, East Sussex on 1 October 2014.

Interserve was contracted to South East Water over an 18-month period at the Crowhurst Bridge Water Treatment Works to improve South East Water’s ability to manage water treatment.

The Environment Agency discovered a brown discharge downstream of the works after a member of the public reported the discoloured water to them.

Further investigations showed that the river was visibly but locally impacted on a temporary basis.

In mitigation it was stated that this was an isolated incident of 25 minutes duration, during an 18-month contract and that the company was of previous good character.

There was no evidence that local wildlife was adversely affected.

David Willis, Environment Manager at the Environment Agency, said: “We take these incidents very seriously and do everything within our powers to safeguard the environment and people that may be affected.”