Bishops Waltham New STW - Wastewater Treatment Plant in Winchester, England

Bishops Waltham New STW is a wastewater treatment plant located near Winchester in Hampshire, England. It serves a population of around 13,752, placing it in the medium agglomeration category under UK and EU regulatory frameworks. As a UK treatment plant, it operates under the Urban Waste Water Treatment Directive (UWWTD) transposed into UK law, which requires secondary treatment for inland plants serving populations between 10,000 and 150,000. The plant's designed capacity is 1.00 (likely in megaliters per day or similar unit), indicating its scale. The treated effluent is discharged into local watercourses that eventually drain into the River Hamble or the River Itchen, both of which flow into Southampton Water and then the English Channel. These rivers support diverse aquatic life and are important for local biodiversity.

The plant's discharge enters local streams that feed into the River Hamble or River Itchen, both of which are ecologically sensitive chalk streams supporting salmonid populations and diverse macroinvertebrate communities. These rivers flow into Southampton Water, a major estuary that provides critical habitat for migratory birds and marine species. The area is part of the Hampshire Basin, a region with significant groundwater resources.