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Pollutions plan

Our current performance against our targets

Putting untreated sewage into rivers is unacceptable to us, to our customers and to the environment. We are absolutely committed to protecting and enhancing our rivers and the communities who love them, and we want to make these discharges unnecessary as quickly as possible.

This is a calendar year performance commitment. In 2021, we narrowly missed our pollutions incidents target, with a year-end position of 271 incidents. This represents a 7% reduction on the previous year. However, we will miss our target for 2022.

Our final performance information for 2022/23 has been published in our annual performance report.

A Thames worker tests the water at a visitor site

What is driving our underperformance

We operate in one of the most densely populated parts of the UK and London is one of the most concreted cities in the world. Our infrastructure sometimes struggles to cope with the volume of sewage that is put into it, particularly during periods of heavy rainfall.

The amount of flow entering our sewers or arriving at the works cannot be controlled and trying to do so would cause flooding somewhere else, from the sewers backing up.

Any surplus, above the amount the site is designed to treat, is diverted automatically to storm tanks and stored until incoming flows reduce and the works once again has spare treatment capacity.

If the treatment works is operating at full capacity and the storm tanks are full any excess overflows automatically to the river, because there is nowhere else for it to go.

Our performance has been adversely affected by the summer drought. This caused lower flows in rivers resulting in discharges having a greater impact than they usually would have had.

How we plan to improve our performance by the end of the AMP

Our plans for improving our performance are set out in our Pollution Incident Management Plan (PIRP). We will publish an updated PIRP later this year.

Since the beginning of the year, we have been publishing live sewage discharge alerts from over 460 permitted locations on our website.

We are the first water company to achieve this level of disclosure, and while we should still expect to be held to account for our discharge performance, our ground-breaking transparency has been widely welcomed.

The completion of the £4.6 billion Tideway tunnel will provide a massive reduction in the need for discharges to the tidal River Thames.