--- title: buenos aires drinks the plata canonical_url: https://ensurance.app/guide/what-buenos-aires-depends-on markdown_url: https://ensurance.app/guide/what-buenos-aires-depends-on.md subtitle: the tap is an estuary. the river on the south edge is a different problem category: ecosystem-services --- # buenos aires drinks the plata *the tap is an estuary. the river on the south edge is a different problem* If you opened the canilla, the kitchen tap, in Buenos Aires this morning, the water in the glass was already finished. Buenos Aires water is taken from the Río de la Plata, the estuary on the city's shore, through intake towers, and treated before it reaches you. It does not come from a reservoir in the hills. It does not come from the river along the southern edge. That southern river is the reason to keep reading. The tap and the Matanza-Riachuelo are the same metro, and they are not the same problem. Ciudad Autónoma de Buenos Aires is the door into this, not the name of the living system. Read the city together with the AMBA, the metro around it, because the concession that treats the water is metropolitan. The Province of Buenos Aires, as a province, is a different geography. ## where buenos aires water comes from **AySA** (Agua y Saneamientos Argentinos S.A.) runs the tap. It takes raw water from the **Río de la Plata** through intake towers and treats it at three surface plants. Two of those plants are General San Martín and Juan Manuel de Rosas. The water those towers stand in is an estuary, a river meeting the sea. Wells are the smaller share. On AySA's potable-water page, well water is 13% of production. They are not the main source. The volume and the people below are AySA's 2023 sustainability figures, from the company's numbers page. The potable-water page carries its own running totals, and those totals stay on that page. In 2023, average treated water was **6,219,234 cubic meters a day**. The concession covers **3,363.51 square kilometers**. **15,103,199** people live in that area. **11,351,535** of them are served with potable water. If you live inside that concession, the morning is this number. The kettle, the school, the shop: 11,351,535 people on a service that starts in an estuary. Treatment can take out what a plant is built to take out. It cannot stand in for the condition of the water the towers are standing in. The city depends on the estuary staying treatable. That is the first dependency, and it runs from the shore to the glass. ## the river on the south edge The **Matanza-Riachuelo** is the other one. Its main stem is **64 kilometers**. The basin is about **2,047 square kilometers**. **ACUMAR**, the Autoridad de Cuenca Matanza Riachuelo, counts **4,703,058** people there, from the definitive 2022 census. The basin takes in fourteen partidos of the Province: Almirante Brown, Avellaneda, Cañuelas, Esteban Echeverría, Ezeiza, General Las Heras, La Matanza, Lanús, Lomas de Zamora, Marcos Paz, Merlo, Morón, Presidente Perón, and San Vicente. Inside the city it takes all of Comuna 8 and parts of Comunas 1, 3, 4, 5, 6, 7, 9, and 10. ACUMAR's documentary center still carries older lines, about 2,200 square kilometers and about 6 million people. The count in this section is the characteristics page. If you live in Avellaneda or Lanús, or in those southern comunas, the 64 kilometers are not a headline from somewhere else. They are the edge. The tap in the kitchen can still be Plata water. The river at the end of the neighborhood is not that tap. The dependency runs back the other way. The basin's people depend on the river the city's sewage has used. A lowland river was asked to carry a megacity's waste and still work as the southern drain. AySA, the same company that treats the drinking water, also runs the Riachuelo system: a collector, an outfall, and a treatment plant. A World Bank paper from August 2025 says those works are in testing, and that the testing already reduces overflows the paper describes. ACUMAR is the basin authority. It is not the company that treats the water. Law 26.168 created it across the Nation, the Province, and the City. The sanitation plan is the Plan Integral de Saneamiento Ambiental, PISA. The 2008 Supreme Court judgment in the Mendoza case ordered a cleanup. In October 2024 the Court ended its supervision. In August 2025 it rejected appeals and reaffirmed that close. Execution stays with ACUMAR. The court stepping back is not the river recovering. The industrial load belongs in the same picture. The World Bank has called the tannery sector a major industrial source on this river. The August 2025 paper said operation of the industrial plant, PTELI, still required tannery relocation, and that the relocation would take years. People in the basin live with that timeline while the sewer works are still being tested. ## both directions The same metro carries both. | dependency | who | on what | |---|---|---| | The tap | 11,351,535 people on potable service, inside a concession of 15,103,199 (2023) | The Río de la Plata staying treatable | | The southern river | 4,703,058 people in the basin (Census 2022) | The Matanza-Riachuelo the city's sewage has used, still functioning as a river | Where the basin crosses the city, a person can be on both rows. A tap from the estuary. A river on the south edge that is not the intake. The company that fills the glass is the company moving sewage toward treatment, and both of those jobs meet this shore. That is the shape of the dependency. :::johnson **buenos aires drinks the plata. the riachuelo is the river it still lives beside.** One metro, two dependencies. The estuary has to stay treatable. The southern river has to remain a river. [see the parent agent →](/parana-river.basin?from=guide) ::: A sudestada, a southeast wind with rain, can hold the estuary up against the drains. The flood risk that remains sits over the Matanza-Riachuelo. The wind is [its own post](/guide/what-a-sudestada-does-to-buenos-aires?from=guide). The contamination is a separate hazard. ## what is already working The people doing the work are already named. AySA operates the intake towers, the surface plants, and the Riachuelo system now in testing. ACUMAR holds the mandate the Court handed back: the statute, the sanitation plan, execution after supervision ended. The architecture exists. Nothing here replaces it. The gap is the living condition beside those works. A collector can move sewage. A plant can make estuary water drinkable on a given day. The estuary and the river beside those works are the living things the works do not replace. The works stay the hero. The Río de la Plata, the intake towers that drink it, and the Matanza-Riachuelo along the city's southern edge exist whether or not anyone buys a certificate. **Ensurance** is how the utility that already runs the tap can fund the living estuary and the living river. It is not the river. The Paraná is the parent outlet of this estuary. The live agent for that parent is [parana-river.basin](/parana-river.basin?from=guide). A line called `matanza riachuelo` is in ideation under that agent. [Co-create it](/specific/create?mode=suggest&agent=parana-river.basin&name=matanza%20riachuelo&from=guide); a person reviews it; the parent agent receives it. [Who already pays for the Riachuelo](/guide/who-already-pays-for-the-riachuelo?from=guide) is where that partnership is spelled out. ## frequently asked questions ### where does buenos aires water come from? From the Río de la Plata. AySA takes it through intake towers and treats it at three surface plants. Two of those plants are General San Martín and Juan Manuel de Rosas. The 2023 sustainability figures put average treated water at 6,219,234 cubic meters a day. Well water is 13% of production, not the main source. ### does the riachuelo supply the tap? No. The Matanza-Riachuelo is the 64-kilometer river on the southern edge. It reaches the estuary. It is not the intake. The tap depends on the Plata staying treatable. The basin depends on the Riachuelo, which the city's sewage has used. ### who runs the plants, and who holds the river? AySA runs the plants and the Riachuelo wastewater system. A World Bank paper from August 2025 describes that system as in testing. ACUMAR is the basin authority under Law 26.168. It coordinates the sanitation plan. It does not treat the drinking water. The Supreme Court ended its supervision of the Mendoza case in October 2024 and, in August 2025, rejected appeals and reaffirmed that close. Execution stays with ACUMAR. ### how many people depend on this? Two counts, and they are not the same map. Inside the AySA concession, 11,351,535 people are served with potable water, out of 15,103,199 people in the concession area (2023 figures). In the Matanza-Riachuelo basin, ACUMAR's figure from the definitive 2022 census is 4,703,058. The city is the door. The concession and the basin are both larger than the city proper. The Province, taken as a whole, is a different geography. ### is the river clean because the court stepped back? No. The Court left the supervision. The river did not become clean because the file closed. The Riachuelo system is in testing. The August 2025 paper said tannery relocation, still required before the industrial plant operates as intended, would take years. A closed supervision is not clean water. ## what comes next Two posts carry the dependency further. [Who depends on the Matanza-Riachuelo](/guide/who-depends-on-the-matanza-riachuelo?from=guide) stays with the people: the basin, the concession, the operator, and the authority. [What a sudestada does to Buenos Aires](/guide/what-a-sudestada-does-to-buenos-aires?from=guide) is the wind, and the flood risk over the southern river. The live parent agent on this shore is [parana-river.basin](/parana-river.basin?from=guide). If this is not your shore, start from [another place](/explore?from=guide). ## sources [AySA, Nuestros números](https://www.aysa.com.ar/Quienes-Somos/nuestros-numeros) — 2023 sustainability figures: average treated water 6,219,234 cubic meters a day, concession area 3,363.51 square kilometers, 15,103,199 people in the concession area, 11,351,535 served with potable water. [AySA, Agua potable](https://www.aysa.com.ar/portal/Que-Hacemos/Agua-potable) — intake towers, three surface plants, General San Martín, Juan Manuel de Rosas, and well water at 13% of production. Running totals on this page are not mixed with the 2023 sustainability figures. [ACUMAR, Características de la cuenca](https://www.acumar.gob.ar/institucional/que-es-acumar/caracteristicas-de-la-cuenca2/) — main stem 64 kilometers, basin about 2,047 square kilometers, 4,703,058 people (INDEC Census 2022, definitive), fourteen partidos, Comuna 8 entire and the partial city comunas. [ACUMAR documentary center, La cuenca](https://centrodocumental.acumar.gob.ar/la-cuenca) — older lines, about 2,200 square kilometers and about 6 million people. Not the figures used above. [ACUMAR, Causa Mendoza](https://www.acumar.gob.ar/institucional/causa-mendoza/) — Law 26.168, the 2008 judgment, and the Court's supervision. [Infobae, 14 August 2025](https://www.infobae.com/judiciales/2025/08/14/la-corte-ratifico-el-cierre-de-la-causa-riachuelo-y-dio-por-concluida-su-supervision-del-saneamiento/) — the Court rejected appeals and reaffirmed the close of its supervision. Used only for that close. [World Bank, August 2025, P105680](https://documents1.worldbank.org/curated/en/099082025172028148/pdf/P105680-60a8b946-e924-4105-8690-a2f3d85c639a.pdf) — the Riachuelo system in testing, overflows that testing already reduces, the tannery sector as a major industrial source, and PTELI operation still requiring tannery relocation measured in years. ## the series 1. [buenos aires drinks the plata](/guide/what-buenos-aires-depends-on?from=guide) (this post) 2. [who depends on the matanza-riachuelo](/guide/who-depends-on-the-matanza-riachuelo?from=guide) 3. [the plata is an estuary, not a tap](/guide/the-plata-is-an-estuary-not-a-tap?from=guide) 4. [a sudestada stacks the plata against the drains](/guide/what-a-sudestada-does-to-buenos-aires?from=guide) 5. [who already pays for the riachuelo](/guide/who-already-pays-for-the-riachuelo?from=guide)