Drainage and flooding

Drainage, flooding and discharge of wastewater

Wastewater generated from site activities including water from dewatering excavations, site run off slurry and bentonite are classified as trade effluent. These should not be discharged direct to surface or foul sewers (these are generally combined in Kensington and Chelsea) without the consent of Thames Water or the Environment Agency and British Waterways for controlled waters (e.g. a canal, river or groundwater). The contractor is responsible for obtaining the necessary consents and ensuring compliance with any conditions imposed on them. The contractor must also minimise the amount of wastewater that needs to be discharged and find alternative means of disposal.

In cases of heavy water run-off, sumps must be provided to avoid surcharging of drains and sewers.

The contractor must implement effective working methods to protect surface and groundwater from pollution and other adverse impacts including changes to water levels, flows and general water quality. 

Legislation and best practice


Codes of practice

Advice for residents

Wastewater drainage

The management and maintenance of the public sewers in London is the responsibility of Thames Water. However, Thames Water states that a sewer connection under the public highway is private and the maintenance responsibility for the drain, including blockages and collapse, lies with the owner/s.

The Council offers to carry out sewer connection reconstruction work as a service to residents. The property owner/s will be charged for this prior to the start of any reconstruction work. You can also arrange for it to be carried out by a private accredited contractor who would have to obtain a street work licence to work on the public highway. The owner/s would have to guarantee the permanent road reinstatement would be carried out in accordance with the New Roads and Street Works Act 1991.

Surface drainage

The surface water drainage of the public highway is the responsibility of the Council. Therefore any blocked road gullies should be reported to Streetline on 020 7361 3001 or [email protected] for repair or renewal.

Last updated: 3 February 2023