SCAYNES HILL STW Wastewater Treatment Plant, Mid Sussex, England

SCAYNES HILL STW is a wastewater treatment plant located in Horsted Keynes, near Mid Sussex in West Sussex, England. It serves a population of approximately 38,000, classifying it as a medium agglomeration under UK regulatory frameworks. The plant is situated inland, away from the coast, and discharges into local watercourses that ultimately drain into the English Channel. As a UK wastewater facility, SCAYNES HILL 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 a plant serving around 38,000 people, secondary treatment is the standard requirement, with tertiary treatment expected if the receiving waters are in a sensitive area. The plant's designed capacity is reported as 1.00, though the unit is unspecified; this likely indicates a capacity in megaliters per day or similar. The plant's treated effluent is discharged into local rivers and streams that form part of the Sussex Ouse catchment, flowing southward to the English Channel. This waterway supports diverse aquatic life and is important for regional biodiversity. The plant plays a key role in protecting water quality in this catchment, particularly given the proximity to the South Downs National Park and ecologically sensitive chalk streams.

SCAYNES HILL STW discharges into the Sussex Ouse catchment, which flows into the English Channel near Newhaven. This river system supports chalk stream habitats, which are rare and ecologically sensitive, hosting species like brown trout and water crowfoot. The plant's treatment helps maintain water quality in this important watershed, which also provides drinking water and supports agriculture in the region.