How we collect and treat wastewater

Our customers can flush and forget because we take care of it. We collect and treat wastewater from three million homes and 200,000 businesses from as far north as Carlisle all the way down to Crewe.

The waste is carried down drains and into our underground sewer network. There are 72,000km of sewers in our region - more than double the distance from Manchester to Sydney, Australia

Wastewater is transported through this network to one of our 567 wastewater treatment works. Once it’s been treated, it’s clean enough to go back into our rivers and seas.

Many of the sewers were built decades ago. To make sure they continue to cope with the amount of wastewater that today’s population generates we’re continuously maintaining and improving our sewer network.


Every year we transport, treat and recycle to land 185,000 tonnes of sewage sludge.
Before we can treat it we transport it from our 567 wastewater treatment works to one of our 38 treatment facilities where we use cutting edge technology to safely and efficiently process it. Not only do our sites ensure we safely and compliantly treat sewage sludge, we also use it to generate clean, renewable energy from the resultant biogas. This biogas is produced, cleaned up and fed into the National Grid or converted into electricity to help power our own treatment works.

The by-products left over from this process are called biosolids. They can be either disposed of at our Shell Green incinerator in Widnes or provided to local farmers to be used as high quality fertilizer.

We have been awarded accreditation from the Biosolids Assurance Scheme (BAS) which was set up by the UK water industry. Member organisations are audited by an independent third-party Certification Body to ensure that they conform to the scheme standards.