Storm overflows pose a persistent environmental and regulatory challenge for water companies. In the UK, more than 450,000 overflow events were recorded in 2024, leading to prolonged discharges of untreated or insufficiently treated wastewater. Although early 2025 data suggest a modest reduction in frequency, the scale of discharges remains high. Regulatory pressure continues to grow: the Environment Act 2021 requires water companies to monitor, report, and progressively reduce storm overflows, while water quality standards and climate driven extreme rainfall further strain sewage treatment works (STWs). This paper presents the IntenSieve CEPT concept as a flexible, cost effective measure to reduce stormwater overflow impacts by making optimal use of existing infrastructure. Under dry weather conditions, the IntenSieve operates as a high rate primary treatment unit, lowering suspended solids, organic load, and associated pollutants, thereby enhancing biological process stability and reducing energy use and sludge production. During storm events, Chemically Enhanced Primary Treatment (CEPT) is activated, allowing diluted high flows to bypass the biological process while still receiving robust physico chemical treatment. The treated bypass stream is then recombined with biologically treated effluent, typically maintaining compliance with consent limits. Demo scale trials in the Netherlands show strong removal efficiencies (e.g., 84% TSS, 62% COD, 85% phosphorus). The compact, modular system enables rapid retrofitting, reduces untreated discharges, and limits regulatory and financial risks.