Esporte Clube Água Santa, commonly referred to as simply Água Santa, is a Brazilian association football club in Diadema, São Paulo, currently playing in the Paulistão, the top tier of the São Paulo state football league.
Founded as an amateur team by migrants in 1981, Água Santa became one of the strongest non-professional teams in the ABC region, winning 17 titles during that time. On 8 December 2011, the team turned pro, joining the Campeonato Paulista Segunda Divisão in 2013. Água Santa won three consecutive promotions in their first years of professionalism, and by 2016, they were already in the top tier of the Campeonato Paulista. They were relegated back to Campeonato Paulista Série A2 after just one season in the top flight. They were promoted to the first division again for the 2020 season, were relegated again in the same year, and won promotion back to the top tier in the following season.
Since the beginning of the professional era, Água Santa has played at Estádio Distrital do Inamar. The club's home colours are white and blue and the team mascot is Neptune, the Roman god of the sea. Their main rivals are São Bernardo, São Caetano and Santo André. Água Santa also had a troublesome off-field relationship with cross-town rivals Clube Atlético Diadema, which resulted in the latter team leaving for Ribeirão Pires.
