Apr 30, 2026 Modernizing Victorian sewers Part of the Thames Tideway Tunnel in London, UK. Part of the Thames Tideway Tunnel in London, UK. Matthew Joseph—Courtesy Tideway London’s Victorian-era sewer system couldn’t keep up with the dual challenges of population growth and climate change. Rainfall regularly overwhelmed the 150-year-old system, sending discharges directly into the Thames River. Now, London’s new £4.6 billion ($6.1 billion) “super sewer”—the largest water infrastructure project in U.K. history—prevents 95% of untreated sewage discharges. Over 10 years of construction, the 15.5-mile Thames Tideway Tunnel created 21 connections with the original sewers to capture, divert, and treat sewage that would otherwise end up in the river. By the time it became fully operational in February 2025, Tideway had already collected 2,200 Olympic-sized swimming pools worth of sewage. A year later, it had collected more than three times that amount.…