As is common in our world, those in Mexico with the least resources suffer the most. Low income and informal neighbourhoods have the least access to safe water, exposing them to high health risks, such as diarrhoea and parasitic and bacterial diseases. Many of them depend on pipas, or water trucks, which aren’t always reliable. The average Mexican family can spend up to 20% of its income on water.

More than 10 million Mexicans lack access to safe water and its capital, Mexico City, is ranked third on the list of cities facing an extreme water crisis. But this is not because of natural water scarcity. In fact, Mexico City receives roughly five months of rain a year and is notorious for flooding.

The problem is due to the the city’s infrastructure and mismanagement of water. In Mexico City, around 70% of water is extracted by aquifers, more than the amount that can be naturally recharged. The city was built over a lake bed and as such, has sunk 10 metres over the past 100 years. What’s more, 30% of Mexico City’s water comes from 150km away through the Lerma-Cutzamala water system, located in an area where many indigenous people themselves face water scarcity. This process of pumping the water from far afield results in high energy costs and 40% of it is lost in transit due to leaky pipes. With roughly 20 million inhabitants, a water crisis in Mexico City is a threat to the whole country.

This is where Isla Urbana comes in. In 2009, the founding team of engineers, designers and sociologists designed a rainwater harvesting system to enable communities to catch rain, filter it and use it for the greater part of the year, without having to depend on an unsustainable system.

To better understand the needs of communities, the Isla Urbana team moved into and worked out of a building in Tlalpan, across the street from the first person to use its system, Clara Gaytan. From there, they began assisting her neighbours. The team conducted pre- and post-construction interviews, trained members of the community and hired local plumbers to install systems.

Cisterns are the most expensive component of the process but, fortunately, most homes in Mexico already have one. This has helped to keep the cost of installations low, from $500 for those who already had a cistern to $1,000 for those who do not. Isla Urbana, a hybrid social enterprise and non-profit, is funded through Mexican government entities, joint projects with NGOs, grants and the Isla Urbana Foundation. Households also contribute 15% towards installation of the rainwater harvesting system to promote ownership and responsibility.

I visited Isla Urbana and Clara’s neighbourhood during a research trip in 2011 and she proudly showed us her system and told us in detail about how it worked. She said the system had changed her life and that she wanted to tell the world.

We also visited other areas of the community that had suffered from lack of water. Story after story was the same; people couldn’t count on the pipas, they had little resources to pay for water and the rainwater harvesting system had vastly improved their quality of life.

The community in Tlalpan became Isla Urbana’s laboratory, enabling the organisation to design an environmentally, socially and economically sustainable model. From the beginning, for example, plumbers were trained and hired from within the communities and the system was created to be low-maintenance, low-cost with easily replaceable parts. Working in urban and rural areas, this has been particularly beneficial for those who cannot easily access materials.

Although their solution has the potential to increase water security for millions, and rainwater harvesting is not a new concept, there has been some resistance to Isla Urbana’s work. Some city officials see it as a bandaid answer to a large-scale problem. For others, the idea of catching rainwater and reusing it is new and seems complicated. But shifting from a linear to a circular economic approach always requires time for adjustment and for Mexico City, rainwater is an abundant resource that should not be ignored in the face of such a crisis.

Through workshops for the general public, educational materials, arts-based programmes and access to personal testimonials, Isla Urbana has been showing policymakers and others that rainwater harvesting is a viable solution.

As of 2016, Isla Urbana has installed 2,200 systems, harvested 170m litres of water and provided for 16,500 individuals. The team has doubled in size and the organisation has now worked throughout Mexico in areas including Jalisco, Durango, Oaxaca, Guerrero, Hidalgo and Chihuahua.

Earlier this year, various government branches agreed to plans for roughly 1,000 systems to be installed throughout Mexico City. This was a significant step as Isla Urbana can start replicating and scaling-up a model developed over time, with the intent of working hand-in-hand with the community, policymakers and partnering NGOs – key steps towards solving the water crisis in Mexico.