Barcelona plans to bring the underground stormwater tank Rambla Prim into operation in 2028. This was announced by Laia Bonet, First Deputy Mayor, during a visit to the existing tank in Park Joan Miró The facility would be the city’s first new construction of this kind in 15 years and part of a strategy to make the drainage system more resilient to heavy rainfall.
According to the Ajuntament de Barcelona The city currently has 15 stormwater retention tanks with a combined storage capacity of around 447,000 cubic metres. The largest tank is beneath Park Joan Miró and holds about 55,000 cubic metres. City documents give Rambla Prim a usable capacity of approximately 90,000 cubic metres. The administration justifies the expansion by pointing to the heavy rainfall in early October 2026, when the tanks reached high levels of capacity and prevented more serious flooding.
Bonet called for the projects to be accelerated. In addition to Rambla Prim, the city is preparing three other schemes: Sagrera, Vallcarca and Bac de Roda. In 2025, the city council had already decided to reserve underground space for the construction of a total of 29 new tanks. Rambla Prim is one of the priority schemes because it is intended to relieve a large catchment area in the north-east of Barcelona.
The city says Rambla Prim will be built in several phases. 2028 is the target year for commissioning the first stage. The administration has not yet given a consistent figure for the total cost; budget documents allocate funds for preparatory work and early construction phases. According to the city, tenders and further funding decisions are expected in upcoming budget and committee rounds.
From a technical perspective, additional retention capacity can ease pressure on the combined sewer system during extreme weather events, reduce overflows into waterways and help treatment plants operate more steadily. Risks include funding several major construction projects in parallel, coordination with network operations and ongoing maintenance. While the stated capacities and projects are documented in city papers, the timing and scope of individual construction phases remain dependent on the progress of planning approval and procurement.
The city administration cites the October storms as the immediate reason for the expansion. Statements about the future benefits of the additional tanks are assessments by those responsible; the decisions and planning documents currently available, and the 2028 target date for Rambla Prim, are the only firm commitments so far.
Editor: Mira Cadena (Article created with AI assistance).