Jose Becker, 57, had been swimming at a dam on his property when the accident happened on Wednesday afternoon, Doroteo Machado Filho, a police inspector in the town of Lavras do Sul, told Reuters. No foul play was suspected.
Liverpool issued a statement asking for Alisson's privacy to be respected.
Alisson joined Liverpool in 2018 from Roma and was voted FIFA Best Men's Goalkeeper in 2019. His older brother Muriel is a keeper for Brazilian side Fluminense.
Internacional, who both brothers played for, tweeted their condolences.
"It is with great sadness that we received the news of Jose Agostinho Becker's death, the father of our ex-goalkeepers Alisson and Muriel," the club said.