Dirty Business is a British docudrama television series written and directed by Joseph Bullman and starring Posy Sterling, David Thewlis, Jason Watkins and Asim Chaudhry for Channel 4.
The series portrays a decade-long investigation into sewage contaminated water by Water Companies in Oxfordshire carried out by two neighbours, Ashley Smith, a former police detective, and Peter Hammond, a Professor of Computational Biology, who notice fish in the local Windrush river are dying, and receive help from a sewage plant whistle blower. The series also follows a family who lost an eight-year old daughter due to E-coli poisoning.
The three-part series is produced for Channel 4 by Halcyon Heart Films and written and directed by Joseph Bullman. It is produced by Laura McCutcheon and Meeshan Saxena with Aysha Rafaele as executive producer. The series is part-based on the real-life campaign group Windrush Against Sewage Pollution (WASP). Members of the production crew and actors met with members of WASP prior to filming.
The cast is led by David Thewlis, Jason Watkins and Asim Chaudhry as well as Posy Sterling, Charlotte Ritchie Tom McKay, Jon Culshaw, Vicki Pepperdine, Craig Parkinson, Charlotte Ritchie, Chanel Cresswell, Lucia Keskin, and Alex Jennings. Filming was completed by January 2026.
The series broadcast on Channel 4 from 23 February 2026.