Horsham STW - Wastewater Treatment Plant in Horsham, West Sussex, England

Horsham STW is a wastewater treatment works serving the town of Horsham in West Sussex, England. The facility handles wastewater from a population equivalent of around 79,000, placing it in the medium-to-large agglomeration category under UK regulations. The plant is situated near the A24 at Broadbridge Heath, within the River Arun drainage basin. As a UK wastewater treatment plant, Horsham STW operates under the Urban Waste Water Treatment (England and Wales) Regulations 1994, which transpose the EU Urban Waste Water Treatment Directive. For agglomerations of this size, secondary treatment is typically required, with additional nutrient removal if discharging into sensitive areas. The plant's designed capacity is 1.00 (likely in megalitres per day or similar unit), indicating a substantial treatment capability. The treated effluent from Horsham STW is discharged into local watercourses that feed into the River Arun, which flows southward through the Sussex Weald to the English Channel at Littlehampton. The River Arun supports diverse aquatic life and is an important river for both ecology and recreation. The plant's operation helps protect the water quality of the Arun catchment and downstream coastal environment.

Horsham STW discharges into the River Arun catchment, which drains through the Sussex countryside to the English Channel. The River Arun supports a variety of fish species, including salmon and sea trout, and its estuary is an important habitat for birds. The plant's treatment processes help maintain water quality standards in the river, which is used for angling, boating, and wildlife conservation.