85% of the world’s population lives in the driest half of the planet, meaning that water is difficult to access for most people (UN Water). Even those that receive high rainfall, sometimes do so only at specific times of the year. When water accessibility becomes inconsistent or even nonexistent, solutions need to be put in place to ensure a steady water supply year round.

Mexico City has more rainfall than London, yet because the necessary water infrastructure systems have not grown with the development of the rapidly expanding city, it suffers from water shortages that are in parallel with a desert. People living in Tlalpan, an area in the south of Mexico City, have to rely on water delivery trucks, known locally as pipas, for most of their water supply. This is also due to their water mains connectivity being particularly bad. Pipas are unreliable, inefficient and expensive.

An Engineers Without Borders UK volunteer, Niall, recently worked with Isla Urbana, an organisation dedicated to designing and installing systems to capture the rain in Mexico. Rainwater harvesting systems are a useful way of collecting water when it rains and storing it until it is needed, which is often throughout a dry period where there is no rainfall at all.

Niall was initially tasked with writing a research paper, investigating the potential for rainwater harvesting systems to meet water demand in Tlalpan. The results were extremely positive showing that our rainwater harvesting systems could satisfy almost the entire needs of an average family during the rainy season. Over 10 years this would avoid the need to make, on average, 2 million pipas journeys. He is now helping to conduct water quality studies on the systems and looking at adoption rates and maintenance. Niall has also worked on building a rainwater harvesting tool that can be used to estimate the potential water savings that can be achieved for a given system anywhere in Mexico based on different inputs of rainfall, roof size and cistern size.

Isla Urbana has installed 1,600 rain water harvesting systems in urban areas and and 60 in rural areas in Mexico. By donating to Engineers Without Borders UK, you are helping us to place essential engineers like Niall in placed they are needed most.