Compton and Marldon STW - Secondary Wastewater Treatment in South Hams, Devon

Compton and Marldon STW is a wastewater treatment facility located in Marldon, South Hams, Devon, England. The plant serves a population of around 2,057 people and is situated in the rural-urban fringe of the South Hams district, within the county of Devon. As a secondary treatment plant, it provides biological treatment to remove organic matter and suspended solids from wastewater. The plant has a designed capacity of 2,413 m³/day and currently discharges an average of 457.96 m³/day of treated effluent. Under the EU Urban Waste Water Treatment Directive (91/271/EEC), which remains implemented in UK law, secondary treatment is the standard requirement for inland freshwater discharges from agglomerations of this size. The facility is part of the UK's regulated water infrastructure. The treated effluent is discharged into local watercourses that ultimately drain to the English Channel via the Dart Estuary or nearby coastal waters. The plant is located within 10 km of the coast, meaning its discharge can influence coastal water quality. The surrounding area includes the South Devon Area of Outstanding Natural Beauty, supporting diverse aquatic and terrestrial habitats.

The plant's discharge enters local streams that flow into the Dart Estuary, a ria system that drains into the English Channel. The Dart Estuary supports important fish populations, including salmon and sea trout, and provides habitat for migratory birds. The coastal waters are used for recreation and shellfish harvesting, making nutrient and pathogen control critical. The plant's proximity to the coast means its secondary treatment level helps reduce but does not eliminate the risk of eutrophication in sensitive marine environments.