The Supreme Court has held that sewerage undertakers have an implied statutory right to discharge surface water and treated effluent from outfalls that were in existence before the coming into force of the Water Industry Act 1991 (WIA 1991). However, there is no such implied right in respect of outfalls from sewers constructed after 1 December 1991.
This is an important decision for sewerage undertakers who will be relieved to know that they can continue to discharge surface water and treated effluent into private watercourses where the sewer outfalls were in place before the WIA 1991 came into force. This can be a valuable right as landowners’ consents are often difficult or costly to obtain.
The Manchester Ship Canal Co Ltd and another v United Utilities Water plc  UKSC