WASHWATER STW - Basingstoke and Deane Wastewater Treatment Plant, Hampshire

WASHWATER STW is a wastewater treatment plant located near Highclere in the Basingstoke and Deane district of Hampshire, England. It serves a population of approximately 6,770 people, classifying it as a small to medium agglomeration under UK regulatory frameworks. As a UK treatment plant, WASHWATER STW operates under the Urban Waste Water Treatment (England and Wales) Regulations, which transpose the EU Urban Waste Water Treatment Directive (91/271/EEC). For agglomerations of this size, secondary treatment is typically required unless the receiving waters are designated as sensitive areas, which may necessitate more advanced treatment. The plant discharges treated effluent into local watercourses that ultimately drain into the River Thames basin, contributing to the wider Thames catchment. The surrounding area includes the North Wessex Downs Area of Outstanding Natural Beauty, and the plant plays a role in protecting local chalk streams and groundwater resources.

WASHWATER STW discharges into local streams that feed into the River Kennet, a tributary of the River Thames. The Kennet is a chalk stream known for its high ecological value, supporting diverse aquatic life including brown trout and grayling. The Thames basin ultimately drains into the North Sea. The plant's location inland and upstream of sensitive chalk stream habitats underscores the importance of effective treatment to maintain water quality.