The Brooklyn mom who allegedly drowned her three young children at a Coney Island beach was ordered held without bail during her bedside arraignment Friday — and could face three life sentences if convicted. 

Erin Merdy, 31, wore a yellow gown as she leaned on the rail of her bed in the psychiatric ward at NYU Langone-Brooklyn and propped her head up with her hand. 

Merdy has remained at the hospital since she was arrested after the pre-dawn Monday drowning of Zachary Merdy, 7, Liliana Stephen, 4, and 3-month-old Oliver Bondarev, according to police. 

Merdy, who spoke in a faint voice, replied “Yes” three times as Judge Archana Rao asked her procedural questions.

Merdy’s lawyer, George Cooke, as well as a police officer, stood nearby during the proceeding. None of Merdy’s family members appeared to be present.

“The defendant had admitted to her relatives that she had hurt her children,” Assistant District Attorney David Ingle said during the arraignment.

Rao ordered Merdy remanded and placed in protective custody, and asked that she undergo a psychiatric evaluation. 

The first-degree murder charge she faces carries a sentence of life without parole.

The arraignment came a day after Brooklyn District Attorney Eric Gonzalez said Merdy is not mentally stable enough to handle an arraignment on murder charges.

Before the Monday morning horror, Merdy left her Neptune Avenue apartment with her three children, walked them down to the sand and allegedly drowned them in the surf, law enforcement sources said. 

Video from the scene shows Merdy walking on the shore with her two older children and carrying the baby in her arms, according to her criminal complaint. 

Cops later found her two miles away from the scene of the drowning, near the Brighton Beach boardwalk. She was discovered barefoot, soaking wet and walking across the sand in a bathrobe. 

A doctor from the city medical examiner’s office determined all three kids died by drowning, and their deaths were determined to be homicides.

Merdy had admitted “that she had hurt her children and that they were gone,” according to the court document. 

Relatives said prior to the incident, Merdy had been acting erratically and appeared delirious.

The family members told authorities she suffered from mental health issues and may have been dealing with postpartum depression after Oliver’s birth.

Merdy had at least two reports of neglect filed against her with the city Administration for Children’s Services for failing to bring the kids to school, but the disposition of the reports is unclear, law enforcement sources said previously.

Merdy is set to appear in court again on Sept. 20.