How EWB-USU gave a Mexican village clean water

EWB-USU students with some of the La Salitrera villagers
The small agricultural town of La Salitrera, México is home to about 100 people. The community has few water sources, including the river that runs through the village and a couple of wells. The most reliable well is two miles west of the town itself. Usually, La Salitrera receives water from that well every three days, but at times it has gone without water for extended periods. Besides lacking a constant water source, the village’s water is often contaminated. There are 20 micrograms per liter of arsenic in the water and other bacteria that can cause illnesses.

Starting in 2009, the Engineers Without Borders Utah State University chapter (EWB-USU) has worked with the community members to come up with a solution to their water issues. The solution? Biosand filters.
Villager adding water to the filte

Villagers adding cement to a biosand filter

The filters use layers of gravel and sand, and a layer of microorganisms, called a biofilm, to treat the water. Learn more about biosand filters and how they work here:

Typically, biosand filters don’t remove arsenic from water, so EWB-USU Team Mexico had to modify them. Using locally available materials such as concrete, washed sand, PVC pipes, and rusty nails, the team created filters to fit the community’s needs. The nails were used to rid the water of arsenic by placing them on a diffuser plate which allowed clean water to pass through and arsenic and bacteria to be removed.
Biosand filter
Filter in La Salitrera

In 2014, EWB-USU students and mentors traveled to La Salitrera with the goal of constructing three filters. With the community’s help, they were able to build twice as many. The community stopped their normal daily tasks in order to help the students. The students with the help of the community put built the filters and taught them how to maintain them. Biosand filters need to have water added every day in order to maintain the biofilm layer, so this was one of the most important aspects to teach to the community. Students held meetings to teach the community how to use the filters, and they went to individuals’ homes to answer and help with any specific questions or issues.

Villager gathering sand from the river
Villagers gathering sand

The biosand filters have more a huge difference in the community. If you would like to learn more about the types of projects EWB-USU focuses on please go to:

Family with their biosand filter


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