UK High Court Justice Finola O'Farrell said she would rule later in the class action case in which claimants are seeking 36 billion pounds ($A75 billion) in damages from Australia-based BHP.
The case was filed in Britain because one of BHP's two main legal entities was based in London at the time.
BHP owns 50 per cent of Samarco, the Brazilian company that operates the iron ore mine where the tailings dam ruptured on November 5, 2015. Enough mine waste to fill 13,000 Olympic-size swimming pools poured into the Doce River in southeastern Brazil.
"As a result of its heavy involvement in Samarco's operations, BHP had many opportunities to avert disaster but failed to do so and instead kept allowing and encouraging the dam to be raised by constantly pushing for ever greater production by Samarco," lawyer Alain Choo Choy said in his closing argument.
A defence lawyer had argued BHP did not own or operate the Fundao dam and the company was not responsible for the pollution.
The company also said a deadline to bring the claims had expired before the lawsuit was filed on behalf of 600,000 Brazilians.
Sludge from the burst dam destroyed the once-bustling village of Bento Rodrigues in Minas Gerais state and badly damaged other towns.
The disaster killed 14 tons of freshwater fish and damaged 660 kilometres of the Doce River, according to a study by the University of Ulster. The river, which the Krenak Indigenous people revere as a deity, has yet to recover.
The trial began in October, just days before Brazil's federal government reached a multibillion-dollar settlement with the mining companies.
Under the agreement, Samarco - which is also half owned by Brazilian mining giant Vale - agreed to pay 132 billion reais ($A37 billion) over 20 years. The payments were meant to compensate for human, environmental and infrastructure damage.
BHP had said the UK legal action was unnecessary because it duplicated matters covered by legal proceedings in Brazil.
Speaking to journalists at an online conference after the hearing, lawyers and victims said they were hopeful BHP would be convicted.
José Eduardo Cardozo, Brazil's former justice minister and a lawyer in the case, said the evidence against the company was overwhelming.
Pamela Fernandes, whose five-year-old daughter, Emanuelle, died in the disaster, has been making trips to London since last year to attend the trial proceedings.
"Just knowing that the trial has come to an end - today was the closing arguments - I already feel very relieved," Fernandes said. "Being here is very painful. "
