Surface water sewer, highway drain or other drainage system
Where no suitable waterbody is present, attenuated discharge to a Water and Sewerage Company maintained surface water sewer is acceptable.
At the planning stage, confirmation from the sewerage undertaker should be provided to show that capacity is available within the existing system to receive flows from the site without increasing flood risk, and any maximum discharge rates.
This should be a developer enquiry application or similar. Within the Royal Borough of Windsor and Maidenhead the sewerage undertaker is usually Thames Water.
If no other option exists, then discharge of surface water to a private sewer or local authority maintained asset may be considered. However, it is highly unlikely that approval to discharge into a highways drainage system will be given.
These systems are usually designed to take a lower magnitude rainfall event (typically one in five year return period) and with capacity to drain the highway extent only. Therefore, any additional connections may increase the risk of flooding to the highway and will not be approved.
Confirmation from the asset owner to show that capacity is available within the existing system to receive flows from the site should be provided.