Cosecha de Lluvia installed 62,700+ residential rainwater-harvesting systems by 2023 — the world's largest such program — as the city battles land subsidence of up to 50 cm per year.
Figures reported by the city programme, verified against published case-study sources.
Background
Built on a drained lake bed, Mexico City faces a paradox: it floods and it runs dry. Over-extraction of groundwater and the compaction of the ancient lakebed cause land subsidence of up to 50 cm per year, cracking pipes and buildings, while depleted aquifers and leaky infrastructure threaten supply for millions.
The intervention
- Cosecha de Lluvia (“rain harvest”), launched 2019, subsidises and installs residential rainwater-harvesting systems, prioritising water-stressed, lower-income boroughs
- Systems capture, filter, and store roof runoff for household use, easing pressure on the aquifer
- Partnerships with organisations such as Isla Urbana for installation and training
Results
By October 2023 the program had installed more than 62,700 systems, making Mexico City the global leader in rainwater-harvesting installations. Studies estimate captured rainwater could meet a significant share of household demand in participating homes.
Lessons
Decentralised rainwater harvesting is not a silver bullet for a sinking megacity, but at scale it reduces aquifer stress, buffers supply shocks, and builds household-level resilience — while the deeper subsidence and infrastructure challenges demand parallel, longer-term fixes.
