Up to 80% of India’s surface water is polluted, according to a 2015 report . But while much of the pollution comes from untreated sewage, industrial waste water is a major contributor, with textile production releasing dyes and unwanted chemicals into rivers.

For small-scale industrial production in rural towns, there often isn’t an easy way to clean this particularly tricky industrial wastewater, which is contaminating bathing and drinking water. But a group of designers and biochemical engineers at University College London have created a leaf-shaped clay tile that can clean heavy metals out of wastewater by capturing these particles in an algae-infused hydrogel. They designed the algae-coated tiles to cover the walls of factories or other buildings. A wastewater tank stored on top of the building, powered by nothing but gravity, would funnel water naturally through the tiles’ vein-like channels.

The tiles, called Indus, use a scientific process called bioremediation, in which biological organisms–in this case, algae–help break down the contaminants, cleaning the water in a sustainable way. This technique has been used since the 1940s to clean up messes on heavily contaminated sites: microbes like algae, bacteria, and fungus can eat plastic and oil spills, and have even found their way into household cleaning supplies that can munch on the oils that are clogging your sink.

As part of the design process, the designers traveled to India and observed the production processes of bangle makers in Kolkata and textile dyers in Panipat, where they found that different batches of fabric or jewelry would produce different types of heavy metals within the wastewater. Through testing, the team found that one particular algae species has the ability to reduce the concentration of the cadmium 10 times within 45 minutes. This algae species was infused into a seaweed-based hydrogel because the gelatinous material is a handy home base for the algae while it’s cleaning the water.

The Indus tiles were fabricated in Khurja, India, the country’s ceramic capital, and the designers worked with locals to experiment with materials and techniques. For the small batch they manufactured, each tile cost between $5 and $7 per square foot depending on which technique they used, though the team anticipates the cost would come down when manufactured en masse.

While this particular prototype was designed for an Indian context, the idea is bigger than that. “We imagine Indus to be adaptable in different regions and continents, made from materials such as sandcrete, laterite, stone, or even waste materials–which are now being increasingly explored in the form of living material composites,” Brenda Parker, a lecturer in biochemical engineering at UCL, tells Fast Company via email.

While the project is still at early stages, the designers also envision building out an entire system of different tiles tailored to specific heavy metals, each with a different algae species that is best suited to each metal. Then, the hope is to install the tiles onto one building to test the viability of the entire system.