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Flood Control: Housing and Roads

Question for Department for Environment, Food and Rural Affairs

UIN HL1604, tabled on 8 July 2022

To ask Her Majesty's Government what analysis, if any, of storm water from (1) the roofs of houses, and (2) highways, they have undertaken to establish whether such water can be discharged safely into (a) water courses, and (b) the sea.

Answered on

26 July 2022

In July 2021, the Environment Agency (EA) produced The State of the Environment: The Urban Environment report (, which includes an overview of the impact of urban and highways surface water run-off in England. Run off from roofs and roads has historically been considered suitable for discharge to watercourses with the overriding driver being efficient drainage to maintain highway safety, but increasingly the impact of this run-off is being better understood, particularly in inland watercourses. There is little risk to the sea because of ample dilution.

National Highways continue to work with the EA to better understand pollutants in road runoff and effective treatment strategies. There is ongoing work to better understand the contribution from the Strategic Road Network (SRN) to micro plastic pollution and to build on earlier research to investigate the presence of other contaminates of potential concern not previously monitored.