E. coli and toxic amounts of fluoride and arsenic in the groundwater meant that people in Guanajuato had to pay US $2 a day for environmentally damaging bottled water or take their chances with the poisoned water supply.

In 2013, Engineers Without Borders UK, through our pro-bono engineers, started working with local partner Caminos de Agua to find a solution.

Ceramic filters

Together, we developed innovative, high-quality filters made of ceramic – a low-cost, locally available substance. These filters – which we refined to make more efficient and cheaper to produce – clean out all the harmful impurities as the water passes through them under the force of gravity.

Such filters are already used across the world, but traditional designs are often large and fragile, and fine cracks can form, allowing contaminants to get through.

The ceramic filters our engineers helped to design in partnership with Caminos de Agua are smaller, more portable and more robust. They are also easier to manufacture, without the need for heavy, expensive machinery.

“Every time we get an Engineers Without Borders UK volunteer, it greatly expands our engineering capability.”

Aaron Krupp, Caminos de Agua

Bone char innovation

We also helped Caminos de Agua set up its own testing laboratory to develop and improve the filters. The lab can carry out microbiological water testing, checking arsenic and flouride levels more cost-effectively and quickly than commercial laboratories.

This has led to an innovation: bone char made from the bones of cows from local butchers’ shops and farms is now being used to remove fluoride from the water.

Health and business benefits

Each filter can clean one litre of water per hour, lasts two to three years and is so cheap that the clean water from these filters is 100 times cheaper than bottled water.

The people of Guanajuato can now drink clean groundwater, save money on bottled water and reduce plastic waste. There are now fewer cases of skeletal fluorosis and developmental difficulties in children.

Local businesses are also benefiting as they produce, maintain and distribute filters, and make bricks for the kilns.