Environmental impact

We use a wide variety of other information to assess risks to customers – and decide whether we need to take action on your behalf. This is part of our approach for holding water companies to account.

Below we highlight the overall performance of the monopoly water and sewerage and water only companies in England and Wales in 2014-15 – and any action we are taking to protect customers’ interests.

Environmental impact indicators

The water sector can have a significant impact on the environment. For example, poorly maintained sewers can lead to the discharge of raw sewage into a river. So the companies are required to maintain their networks and manage their operations effectively.

The company reports and data from the quality regulators tell us there were significantly fewer serious pollution incidents caused by water company sewerage assets last year. At an industry level there were around two incidents for every 10,000km of sewer in 2014 compared with around three incidents for every 10,000km in 2013. There was also a  decrease in less serious incidents with 71 for every 10,000km in 2014 compared with 83 for every 10,000km in 2013. Companies have explained where they are focusing work to reduce pollution further in future.

In other news, the companies reported that together they emitted the equivalent of about 4 million tonnes of carbon dioxide in 2014-15. This is about the same as the previous year. The activities the companies carry out can generate a large volume of greenhouse gases. For example, treating and pumping water and sewage uses a lot of energy. The companies are expected to reduce their emissions where it is economic to do so and in customers’ interest.

Action we are taking

Where companies have identified issues with their performance, we are following these up with them to make sure they get back on track.

If companies fail to deliver the agreed environmental performance, we and the Environment Agency will consider together what action we each need to take to protect the environment and customers’ interests.

The Environment Agency sets legal requirements that the companies must meet to protect the environment. So, it is responsible for taking action if the companies fail to deliver these requirements. You can read more about this in Environmental performance of the water and sewerage companies in 2014.

We are responsible for making sure that the companies deliver the environmental improvements that customers pay for in their water and sewerage bills. We can take action where the companies fail to deliver these improvements – for example, by making them pay back money for things they did not deliver. We clawed back more than £60m for customers for not companies not delivering the level of service customers would expect on pollution incidents.


We have collated below the performance data companies have published.

Greenhouse gas (GHG) emissionsPollution incidents sewerageSerious pollution incidents seweragePollution incidents (water)
Discharge permit complianceSatisfactory sludge disposal
Dŵr Cymru26158.82.299.1%100%
Severn Trent49163.91.699.9%100%
South West150169.23.396.1%100%
United Utilities47449.00.598.0%100%
Affinity Water122
Dee Valley9
South East814.8
South Staffordshire – Cambridge area7
South Staffordshire – South Staffs area57
Sutton & East Surrey29

Green means the company’s performance is in line with or better than expected
Amber means the company’s performance is not in line with expectations but performance has slipped only slightly
Red means the company’s performance is significantly below target or expectation
Grey means companies did not have to submit this data