Anglian Water has been ordered to pay £156,000 for sewage pollution.

The court found that negligence and a lack of maintenance were to blame for the pollution of a Northamptonshire brook.

The pollution occurred over 2 days in August 2016, when at least a kilometre and a half of Grendon Brook was contaminated with sewage.

Tests carried out by Environment Agency officers at the time showed levels of ammonia were 20 times higher downstream – enough to be extremely toxic to fish, invertebrates and other aquatic life.

The pollution was caused by various failures at the pumping station, which takes in raw sewage and transfers it to the main site for treatment. The pumps became air-locked and stopped working, causing sewage to back up in the storage tank, which filled and discharged into the nearby brook. Alarms which should have alerted staff to the problem also failed to sound.

Investigations found the faults were due to a lack of maintenance – and although Anglian Water had undertaken three maintenance visits, they had no records of the affected parts being cleaned or maintained in the year leading up to the incident.

The fine follows a recent £350K Enforcement Undertaking, to be paid to the Westcountry Rivers Trust by South West Water, and a £700K fine for Thames Water.