The Companhia Catarinense de Águas e Saneamento (CASAN) is a Brazilian company, public and mixed economy, with publicly traded capital and operating as a concessionaire in the basic sanitation sector.

Considered one of the largest companies in Santa Catarina, Casan is responsible for benefiting more than 2.7 million people, equivalent to 39% of the state's population. Its coverage extends to 195 municipalities in Santa Catarina and 1 in Paraná.

In this sense, its operations in the municipalities occur through contracts and agreements, the legal instruments established with city halls, which guarantee the company's right to provide management, operation, and maintenance services for water supply systems, sewage collection, and treatment.

Casan also supplies water in bulk to four municipalities that operate with their own systems and together serve more than 200,000 people. Thus, with coverage in a large part of Santa Catarina, the operation involving the sanitation systems is coordinated by Casan's headquarters (Florianópolis) and the four regional superintendencies, spread across the North/Itajaí Valley, West (Chapecó), South/Serra (Criciúma), and Greater Florianópolis.

Casan was created on December 31, 1970, through State Law No. 4,547 and constituted on July 2, 1971, with the objective of carrying out tasks such as coordinating planning, executing, operating, and exploring public sewage and potable water supply services, in addition to carrying out basic sanitation works in municipalities of Santa Catarina.

The company also inherited 16 water supply systems and two sewage collection systems from the former Autonomous Department of Sanitary Engineering. Currently, the services provided by the company cover the entire state of Santa Catarina and are divided into four regional superintendencies.

Casan's first project took place in 1972, and since then the company has always sought to contribute to the improvement of the quality of life of the population of Santa Catarina. Its operations, however, are a key factor for economic and social development in its concession area.

With the completion of its IPO in 1998, Casan became listed on the Stock Exchange. Currently, it is responsible for serving more than 2.7 million people located in 195 municipalities in Santa Catarina. In 2019, the state of Santa Catarina became the main shareholder of the company, holding about 64.21% of the shares.