The situation is better than last year; Summer starts this Sunday and ends March 20, 2026
On the eve of the official start of summer, 19 of the 175 beaches on the São Paulo coast monitored by Environmental Company of the State of São Paulo (Cetesb) are not suitable for swimming. The report, published on Thursday 18, shows that all the other 156 beaches carry the green flag, which signals good quality sea water. Summer begins this Sunday 21 and ends on March 20, 2026.
The situation is better than last year. At the start of summer, in December 2024, the coast of São Paulo had 28 unsuitable beaches, including 13 on the north coast. This time there are only five red flag beaches on the north coast, including Praia do Itaguá in Ubatuba. The beach appears twice in the Cetesb list because, because it is large, it has two monitoring points, in the center and in the right corner.
The other 14 are in Baixada Santista. Santos and Praia Grande have the highest number of unsuitable beaches: four each. São Vicente has three Red Flag beaches, Itanhaém and Peruíbe, one each.
Last week’s monitoring revealed 16 unsuitable beaches across the coast. According to the agency, this increase could be linked to recent rains that hit the coast before the samples were collected. Rain washes organic matter into the sea, including illegal sewage.
175 supervised beaches
In São Paulo, Cetesb monitors 175 beaches, covering the entire coast, from Ubatuba, on the border with Rio de Janeiro, to Cananéia, on the border with Paraná. Collection follows a national standard: it is weekly and always carried out at the same point, to guarantee comparability. The sample is collected from the area where the swimmer enters the sea and taken for microbiological analysis in the laboratory to detect bacteria, such as enterococci.
Cetesb has been monitoring the quality of São Paulo’s beaches since 2001, in accordance with a resolution of the National Environmental Council (Conama). The agency considers a beach unsuitable for swimming when the water has more than a hundred colonies of bacteria per 100 ml of water, in two or more samples, over a period of five weeks.
When a beach is thus classified, the strip of sand is marked with red flags.
The “unsuitable” classification indicates that the water quality is compromised, increasing the risk of contamination for bathers and making the use of the beach for swimming inadvisable.
In addition to high concentrations of fecal bacteria, a beach may also be classified as unsuitable in other situations that discourage direct contact with water. These situations include: the presence of oil due to oil spills, the occurrence of red tide, potentially toxic algae blooms or outbreaks of waterborne diseases.
38 thousand properties without wastewater collection
Beach water quality may be linked to urban sanitation. According to Sabesp, a basic sanitation company that serves towns across the region, thousands of homes in beach towns have a curbside collection network, but are not connected to it.
In Baixada Santista alone there are 30,000 properties in this state. On the north coast there are over 8,000 properties. These properties can contribute to environmental pollution. The sewerage system is separate from the rainwater drainage system. While sewage is treated, rainwater flows into springs that flow into the sea, carrying dirt, waste, animal waste and sewage that is not collected properly.
Sabesp indicated that in all the coastal towns it serves, the sewerage system is functioning normally.
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