The Billings Reservoir is one of the most striking landscapes in the São Paulo Metropolitan Region and, at the same time, one of the most misunderstood. For drivers on the Imigrantes highway or the Rodoanel, it is a sheet of water between hills. For people living in Ribeirão Pires, Rio Grande da Serra, São Bernardo do Campo, Santo André or Diadema, it is leisure, scenery, a source of water and, often, a cause for concern. This guide brings together the reservoir’s history, its role in power generation, its water supply, the laws that protect it and the problems that still threaten it.
A reservoir built to generate power, not to supply water
The first surprise for many people is that Billings was not built to quench the region’s thirst. It was built to generate electricity. The idea is tied to engineer Asa White Kenney Billings (1876–1949), who worked for Light, the company that supplied São Paulo’s power at the time. According to Wikipedia, in 1923 he proposed damming the Rio Grande, also known as the Jurubatuba, instead of following the company’s earlier plan. Diário do Grande ABC reports that the project is dated March 27, 1925, a date the newspaper treated as the reservoir’s centennial in 2025.
Construction advanced in stages. The Rio das Pedras dam began in 1925 and the area was flooded in 1927. In 1937, Light started the Rio Grande dam. In the 1940s, the Pedreira and Traição pumping stations were built to increase the system’s flow, a decision that brought serious environmental consequences, as we will see below. The name Billings, honoring the engineer, was adopted in 1949, according to Sesc. Since 1998, power generation has been operated by Emae, Light’s successor in that area.
How plateau water becomes electricity on the coast
The secret of the project is the terrain. Billings sits on the plateau, very close to the edge of the Serra do Mar. On the other side of the mountains is Cubatão. The stored water is diverted through a canal and drops down the escarpment to the Henry Borden power plant at the foot of the range, using a vertical drop of about 720 meters.
The complex has two powerhouses, one external and one underground, with 14 generating units in total. The underground plant, dating from 1956, is listed by English-language Wikipedia with a capacity of about 880 MW. In a statement to Diário do Grande ABC, Admilson Barbosa of Emae stressed the reservoir’s “strategic and multifunctional importance.”
A reservoir with eight arms, and numbers that vary by source
Billings has a highly indented shape, with eight main arms: Rio Grande, Rio Pequeno, Capivari, Pedra Branca, Taquacetuba, Bororé, Cocaia and Alvarenga. It touches, in whole or in part, the municipalities of São Paulo, Santo André, São Bernardo do Campo, Diadema, Ribeirão Pires and Rio Grande da Serra.
When it comes to measuring the reservoir, each source gives a different figure, usually because they use different criteria. Diário do Grande ABC cites about 150 km² of water surface and 463 km of shoreline. Portuguese-language Wikipedia gives 10,814 hectares (about 108 km²), the English version says 127 km², and a Sesc text mentions 106.6 km² and 995 million cubic meters of water. For that reason, this guide always attributes figures to their source and avoids settling on a single value.
Where the water in ABC taps comes from
Although it was designed for energy, Billings came to supply people with water. Since 1958, the intake on the Rio Grande arm has provided drinking water. In 2000, the intake on the Taquacetuba arm went into operation. These are the only two stretches of the reservoir used by Sabesp for drinking water; the rest of the reservoir is not intended for consumption.
To protect the Rio Grande arm, a barrier separating it from the main body of the reservoir was built in the early 1980s. The Rio Grande system has a capacity of about 11.21 billion liters, and its treatment plant produces roughly 5,500 liters per second, serving São Bernardo do Campo, Santo André and Diadema. According to Sabesp, the system supplies about 1.4 million people. Other publications cite 1.8 million or “over 1 million,” a difference that also depends on how people are counted.
Pollution: a problem that began in the 1950s
The region’s unplanned growth, mainly between the 1950s and 1970s, brought household sewage, industrial sewage and heavy metals into the reservoir. Another chapter was the pumping of Rio Pinheiros water into Billings. In 1992, reversing the Pinheiros into Billings was banned and, according to Wikipedia, a 2010 resolution again allowed pumping during periods of heavy rain.
On July 13, 2009, Governor José Serra signed, in Rio Grande da Serra, State Law No. 13,579, which defines the Billings Watershed Protection and Recovery Area (APRM-B). The law requires, among other measures, that homes be connected to the sewage network, and sets a 50-meter restricted strip from the maximum operating level. Environmental lawyer Virgílio Alcides de Farias, of the Movimento em Defesa da Vida do Grande ABC, notes that Billings’ waters are classified as classes 1 and 2, which prohibits sewage discharge, even treated sewage.
Experts quoted in the press are cautious. Professor Renata Maria Moreira of UFABC believes improvement will not be quick. Farias warns that, without action, the central area of the reservoir could become a polluted receptor in about 50 years.
Billings in 2026: sewage, algae and the Rio Pequeno project
Two recent news stories show the reservoir remains at the center of the debate. The first concerns water quality. A report by USCS (Municipal University of São Caetano do Sul), commissioned by the Rio Grande da Serra city government and produced in November 2025, mapped 16 points of irregular sewage discharge into water bodies that feed the Rio Grande arm. The Water Quality Index at those points was rated “very poor.” The city identified more than 30 areas with sewage flowing directly into streams, 16 of them in critical condition. USCS biologist Marta Marcondes highlighted the presence of many disease-causing microorganisms.
The Diário do Grande ABC report of March 27, 2026 also shows the authorities’ response. According to Mayor Akira Auriani, Sabesp committed to bringing forward universal sewage treatment in the city from 2030 to 2028, with R$ 400 million in investment. The state Secretariat for the Environment, Infrastructure and Logistics (Semil) confirmed the irregular points and said Cetesb is carrying out inspections; universal sanitation is set for 2029 under the concession contract. In Santo André, an arm near Jardim Miami and Riviera shows a heavy concentration of algae, known as macrophytes, which multiply in highly polluted environments, along with solid waste.
The second story is the Rio Pequeno water transfer. On January 21, 2026, Sabesp began works to link the Billings system to the Alto Tietê system. The project plans to draw water from the Rio Pequeno arms in São Bernardo and pump it to the Taiaçupeba Reservoir in Suzano through a buried steel pipeline of about 38.1 km, with an intake of 4,000 liters per second and an investment of R$ 1.4 billion. The route crosses Santo André, São Bernardo, Ribeirão Pires, Rio Grande da Serra, Suzano and Mogi das Cruzes.
Sabesp says the work responds to scarce rainfall and is part of the Water Security Plan, which runs to 2060. Director Marcel Costa said eight routes were analyzed, that the chosen one is the most environmentally suitable, runs along public roads and holds a Cetesb license. Semil said a study by FCTH, at USP, confirms the intake is viable. On the other side, Marta Marcondes questions the impact on vegetation and on the springs that feed the Rio Grande arm, as well as the lack of public hearings, and recalls that an emergency interconnection built in 2014–2015 allegedly silted up about 1 km of that arm. The Rio Grande da Serra city government and its Municipal Environment Council also voiced concern, and Santo André’s Semasa pointed to technical inconsistencies in Sabesp’s assessment. The debate is ongoing and worth following.
Leisure, fishing and water sports: Billings is also for enjoying
Despite its problems, the reservoir remains one of the most prized leisure settings in the region, with small beaches, viewpoints, restaurants, sport fishing and water sports. Fish mentioned by the sources include tilapia, lambari, carp and traíra. To find out where to sail, kayak, stand-up paddle and fish, what precautions to take and how to get there, read our guide to water sports, fishing and leisure at the Billings Reservoir.
If you want to turn the outing into a full weekend, you can combine the reservoir with other nearby destinations. Our complete guide to Ribeirão Pires covers attractions, food and itineraries, and the Paranapiacaba guide shows the English-style village in the Serra do Mar, just a few kilometers away.
Summary: what you need to know about Billings
- Origin: a 1925 project tied to Light, built to generate power at the Henry Borden plant in Cubatão.
- Water supply: only the Rio Grande (since 1958) and Taquacetuba (since 2000) arms provide drinking water.
- Municipalities: São Paulo, Santo André, São Bernardo do Campo, Diadema, Ribeirão Pires and Rio Grande da Serra.
- Protection: State Law No. 13,579/2009 (APRM-B), which requires sewage collection and a restricted strip.
- Challenges in 2026: irregular sewage discharge, algae and the controversial Rio Pequeno water transfer project.
Sources consulted
- Diário do Grande ABC – Criada para gerar energia, Billings hoje fornece água para a região
- Diário do Grande ABC – Billings completa 98 anos
- Diário do Grande ABC – Billings 101 anos: USCS mapeia 16 pontos de descarte irregular de esgoto
- Diário do Grande ABC – Sabesp inicia obras para transposição de águas do Rio Pequeno
- Diário do Grande ABC – Projeto da Sabesp envolvendo Billings ameaça abastecimento da região
- Wikipedia (PT) – Represa Billings and Billings Reservoir
- Sesc São Paulo – Represa Billings
- Migalhas – Governador de SP sanciona lei da Billings
Information current as of October 23, 2026. Figures for area, population served and project status may change; always check official bodies. Most sources listed are in Portuguese.
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