Henfield STW Wastewater Treatment Plant, Horsham, West Sussex

Henfield STW is a wastewater treatment facility located near Henfield, Horsham, in West Sussex, England. The plant serves a population of around 5,379 people, classifying it as a small agglomeration under UK water industry standards. It is situated inland, approximately 50 km from the coast, and its treated effluent ultimately drains into the English Channel via the River Adur catchment. As a UK wastewater treatment plant, Henfield STW operates under the Urban Waste Water Treatment (England and Wales) Regulations 1994, which transpose the EU Urban Waste Water Treatment Directive. For a plant of this size, secondary treatment is typically required. The plant's designed capacity is 1.00 (likely in megaliters per day or similar unit), indicating its scale relative to the population served. The treated wastewater from Henfield STW is discharged into local watercourses that feed into the River Adur, which flows through the South Downs National Park and into the English Channel at Shoreham-by-Sea. The river supports diverse aquatic life and is an important habitat for species such as brown trout and European eel. The plant plays a key role in protecting water quality in this sensitive chalk stream environment.

Henfield STW discharges into the River Adur catchment, a chalk stream system that flows through the South Downs to the English Channel. The river supports diverse aquatic life, including brown trout and European eel, and is ecologically sensitive due to its chalk stream characteristics. The plant's effluent contributes to the overall water quality in the catchment, which is important for downstream habitats and recreational use.