The drama, which includes testimonies from whistleblowers, shows how Margaret Thatcher’s privatisation of the water industry in 1989, combined with David Cameron’s drive to slash regulation, transformed Britain’s sewage systems. Where once, according to one retired Thames Water engineer, it was run like a “military operation”, priorities shifted. Spending and investment fell away, while water companies extracted billions in profits. The catalogue of treatment plant failures, malfunctions and overflows resulted in a policy of flushing untreated sewage straight into our waterways. In 2024 alone, water companies dumped raw sewage into England’s rivers and seas for 3.61m hours.