The European Investment Bank (EIB) is lending the City of Stockholm 5 billion Swedish kronor, about 470 million euros, to fund what is being described as the city's most significant environmental investment in decades.
The financing will support a comprehensive consolidation of Stockholm's wastewater infrastructure. The existing Bromma treatment plant will be decommissioned, and all sewage will be redirected to two upgraded underground facilities: the Henriksdal plant, responsible for secondary, tertiary and sludge treatment, and the Sickla facility, which will handle primary treatment. A new underground collection tunnel will form the backbone of this transfer, gathering sewage from the western part of the city and routing it to both plants.
Henriksdal will be retrofitted with advanced membrane bioreactor technology, increasing treatment capacity without expanding its physical footprint. The upgraded system is also designed to strengthen climate resilience, ensuring the network can handle heavy rainfall events and reducing the risk of stormwater overflows into Lake Mälaren, Stockholm's primary source of drinking water.
The environmental outcomes are significant. Upon completion, nitrogen discharges into the Baltic Sea are projected to fall by around 40% and phosphorus loads by approximately 35%. The system will also capture microplastics and lay the groundwork for removing pharmaceutical residues in the future. The project is designed to meet the requirements of the revised Urban Wastewater Treatment Directive (EU/2024/3019) and the Baltic Sea Action Plan recommendations.
EIB Vice-President Karl Nehammer underlined the investment's strategic importance: "This is an investment in a cleaner sea and a more secure water supply. By supporting Stockholm's new treatment solution, we are helping to reduce discharge into the Baltic Sea and strengthen the city's climate change adaptation measures."
Stockholm's City Treasurer, Sofie Nilvall, welcomed the partnership: "We appreciate the EIB's continued support for the City of Stockholm's loan financing. This time it concerns one of our largest projects, the expansion and modernisation of the Henriksdal wastewater treatment plant, which will strengthen the city in several areas, including the environment, public health and preparedness."
The total investment stands at SEK 19.5 billion (approximately EUR 1.8 billion), with the EIB loan covering roughly 26% of that figure. The financing is being provided with a long maturity to match the programme's implementation timeline, with completion scheduled for 2031.
