Buenos Aires Against Water Pollution: How To Protect The Rio de la Plata Basin

In early February 2025, the Sarandí Canal, which runs through the southeastern outskirts of Buenos Aires, turned a bright red, triggering immediate alarm among the residents of the capital of Argentina and surrounding areas. This canal is one of the tributaries of the Río de la Plata, the widest river in the world, along whose banks three water treatment plants ensure potable water for the city and its entire metropolitan area.

According to some local media, the altered color of the Sarandí’s waters was likely caused by the illegal discharge of textile dyes from local tanneries. “This is not the first time something like this has happened. Over the years, we’ve seen the canal in every color,” a woman living along the stream told Argentine television. “It’s turned blue, green, pink, purple, and once it even looked like oil because it was covered in a layer of grease.”

Unfortunately, for many years, the rivers that flow through the industrial areas of Buenos Aires have suffered from severe water pollution. In response to this situation, in 2006, local residents filed a class action lawsuit against the Argentine government. After two years, they successfully won recognition of their rights. The Argentine Supreme Court subsequently ordered the implementation of several major water pollution solutions.

The most significant initiative has focused on the Riachuelo River, a 64-kilometer-long tributary of the Río de la Plata (not far from the Sarandí Canal) and historically known as one of the most polluted rivers in the world. Unlike the Sarandí, however, the future of the Riachuelo looks much brighter, thanks to a large-scale water management and treatment project nearing completion.

For 150 years, the Riachuelo (also known as the Río Matanza) has been subjected to unregulated industrial waste dumping from factories along its banks and has suffered from river pollution caused by unmanaged stormwater and illegal sewage connections.

Unfortunately, its floods affect very populous neighborhoods such as La Boca or Barracas, generating a very high environmental impact on the population, which pushed the government to implement the “Riachuelo System“, a project designed to manage and clean the river’s polluted waters, benefiting 4.3 million people.
The project has been divided into three phases. The first involved constructing a network of underground tunnels to collect polluted water from the Riachuelo and channel it to a water treatment plant located on the shores of the Río de la Plata.

The second phase, nearing completion and led by Fisia Italimpianti (a subsidiary of the Webuild Group, a global leader in water treatment infrastructure), involves the construction of the water processing plant itself.

The third phase (already completed by Webuild) saw the construction of a new system of underground and underwater tunnels stretching 12 kilometers from the water treatment plant into the heart of the basin, where treated water will be safely released.

Ensuring the water treatment of the Riachuelo’s polluted waters and protecting Buenos Aires is one of the most challenging water projects in the world. The first pipeline network (Phase 1) runs 40 meters underground to the water treatment plant, which Fisia Italimpianti is now finalizing. There, a series of hydraulic pumps will push the water to the surface for processing.

Once treated, the water will be returned to a depth of 40 meters and funneled into a second pipeline network, which will transport it to the Río de la Plata. The treated water will be discharged into the outlet tunnel at an average flow rate of 27 cubic meters per second, handling 2.3 million cubic meters of wastewater daily. These figures make the Riachuelo System one of the largest water treatment plants in the world in terms of capacity, representing groundbreaking infrastructure for the future of Buenos Aires.