What if we embraced vernacular biomaterials to filter water?
We spent two months working with the teams at Space 10 and TU Delft to explore visions for resilient water futures for megacities around the world. While most of our work at Casa Tamarindo is centered around Las Californias, we were excited to dive into solutions for Mexico City.
Water scarcity is an increasingly urgent problem. "Demand has already outpaced population growth, with urban water demand set to increase by 80 percent by 2050. But most cities are not water-resilient, generating competition and putting pressure on surrounding regions — so much so that half the world’s population is already experiencing severe water scarcity at least one month a year. In short, our progress on Sustainable Development Goal 6 is precariously off track." - Linsey Rendell
Empty water jugs being taken via boat to be refilled across Lake Xochimilco. This lake, with a complex series of floating gardens and canals (sometimes called the Venice of Mexico) is what's left of the efforts of the Aztec people who built their thriving Capital city within Lake Tenochtitlan.
Why Mexico Ciy?
Mexico City is one of the planet’s most absurd urban paradoxes — it’s a dense, wet, and viciously thirsty city built directly on top of a network of lakes. This concrete jungle birthed out of uninformed decisions and an aggressive demand for growth is nestled in a basin of unstable layers of clay and lava rock preventing water from naturally refilling the aquifers. Replacing a brilliantly managed system of levees, lakes, and canals created by the Aztecs, modern-day Mexico City grapples with its contradictory relationship to its natural and urban geology.
We initially wanted to resolve the big, city-wide issue: that when it rains, it pours, and then it floods. Yet with all that water, people are still thirsty. Today, the city faces a paradox — too much contaminated floodwater and too little drinkable water. It’s a complex ecosystem in need of decolonizing.
Locally, there’s a tendency to seek solutions from other parts of the world. We knew throwing money and innovation into city-wide designs could only go so far. So, we talked with people who are experiencing this reality firsthand, with the hope it would lead us to a genuinely local response. While the city is busy repairing expensive and massive infrastructure problems there are a few local initiatives that focus on filtering rain or wastewater. Yet the materials used are imported from Europe or China, creating a dependency on yet another globalized supply chain. We turned to the surrounding bioregion for answers.
Mendoza codex 1541 the first documented history of the Aztecs and current flag of Mexico both show an Eagle on top of a cactus growing out of lava rock on water. The symbol comes from the Aztec legend that said the people would know where to build their Capital city (Tenochtitlán) once they saw an eagle eating a snake on top of a lake. After colonization, the Spanish also symbolically included the rattlesnake to represent the triumph of good vs. evil with the snake representing the serpent in the Garden of Eden.
While researching low-tech water filtration methods, we found the answer was right in front of us: nopal (prickly pear cactus), a traditional and plentiful source of food that grows symbiotically with tezontle (lava rock) all over Mexico City are so culturally significant they appear in the Mendoza Codex and on the flag of Mexico.
NOPAL (Prickly pear or cactus)
Nopal mucilage, or "goo", acts as a flocculant, where heavy metals and contaminants congeal together and can be removed. Research has shown nopal can clean contaminated water 300 times more efficiently than aluminum sulfate, a commonly used filtration agent which is energy and chemically intensive. Removing the goo from the pad is as simple as juicing or blending it.
TEZONTLE (Lava rock or pumice)
Lava rock is found all over Mexico City and has been used in architecture throughout history. The porous qualities of lava rock make it act like a sponge when combined with nopal mucileage As the goo works it's flocculating magic, contaminants stay trapped in the highly absorbent material.
While we believe these biomaterials have huge potential at city-wide scales, we wanted something more tangible for individuals. Inspired by the Aztec pyramids and famous architect, Luis Barragan, the AKUA water filter acts like a simple biosand filter for the home.
The piece can be made entirely within the city. We see it as a way to give power back to the people and inspire connection to Mexico City’s extraordinary lake ancestry.
Click on the images below & see how to do it yourself.
Please note, we do not claim to be water experts. While new research is happening surrounding nopal for water filtration, there is still much work to be done.