Pollution reporting

We’re responsible for the safe transportation and storage of large quantities of wastewater along with the chemicals needed to treat it. We're careful to prevent them escaping our network and posing a risk to nature or wildlife.

Pollution incidents can happen for a number of reasons – from a blocked sewer causing sewage to back up and escape through a manhole, to a cracked pipe leaking wastewater into the environment.

We publish our annual pollution figures here (last updated March 2021).


Our pollution performance

The Environment Agency records pollution incidents under three categories based on impact to the environment:

  • Category 1 incidents have a serious, extensive or persistent impact on the environment, people or property
  • Category 2 incidents have a lesser, yet significant, impact
  • Category 3 incidents have a minor or minimal impact on the environment, people or property with only a limited or localised effect on water quality
  • Self-reported – where we report an incident to the Environment Agency before it's reported by a third party, it's also recorded as a 'self-reported incident'.

The graph below shows our performance for sewerage pollution by year, as recorded by the Environment Agency:

In 2020, we saw a 40% improvement in pollutions from wastewater treatment works and a 10% improvement overall. No Cat 1 pollutions were reported, showing an improvement in our incident management processes.

In recent years, we’ve rolled-out pollution awareness training and ethical decision-making practices to our employees. As a result, we’re getting better at identifying and reporting events that could cause harm to the environment.

The increasing percentage of self-reported pollutions indicates these cultural changes have been successfully embedded. However, we believe this improved level of self-reporting is partly responsible for the increased number of pollution incidents recorded in recent years.


Our pollution data

For more detailed information about our pollution performance for each calendar year, please download the .xlsx spreadsheet below.

Pollution performance data 2015–20

CSV data files for each year are also available: 2015, 2016, 2017, 2018, 2019, 2020.


Our pollution reduction programme

We’ve set an ambitious target to reduce pollution incidents to 80 by 2025 and zero by 2040.

This is part of our pollution reduction programme, which will deliver a big step-change in how we work, prioritise and remedy issues on our sites – including focusing our attention and investment on areas which will deliver the biggest reduction in pollution incidents.

You can help too. If you see something that you think might be a pollution get in touch on 0330 303 0368 – together, we can protect and improve the environment.

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