A north Queensland single mother found guilty of manslaughter over the bathtub drowning of her nine-month-old son while she was socialising with a family member in another room will spend at least one year in prison.

In the Supreme Court in Townsville on Monday, Kandita Kattenberg, 29, a mother of five, was sentenced to four years for the manslaughter of her youngest son, Carlyle, in Charters Towers on November 9, 2016.

In handing down the sentence, Justice David North said Kattenberg's "criminal neglect was patent and obvious".

The court heard Carlyle was not sitting in his bathing seat properly and he slipped out while the water was running.

Crown prosecutor Nathan Crane said Kattenberg left her eldest son, then 10, to supervise Carlyle in the tub that night, but then called him away.

He said the boy started playing with other children, but when Kattenberg thought the water was running she sent him to check on Carlyle.

The boy found Carlyle unconscious, took him into the lounge room and tried to revive him.

Mr Crane said Kattenberg often gave her eldest son the responsibility of watching Carlyle in the bath, which could take up to two hours.

"She continually placed her child in a vulnerable position," Mr Crane said.

He said in another incident before Carlyle's death, Kattenberg left the baby in the bath, fell asleep and then woke hours later to find him wrinkly and still in the water.

"It does reflect that there was a warning sign," Mr Crane said.

Kattenberg had shown "criminal neglect" and had set a dangerous bath routine, Justice North said. ( Facebook: Kandi Kattenberg )

Justice North said while she might have often been busy, this had been a routine practice.

"There was a pattern of dangerous neglectful care that you persisted with and on at least one occasion prior to the incident that should have acted as a wake up call to you," he said.

"This is not a case of death by violence but a case of death by neglect, set up in the context of the dangerous routine where you exposed a young child to great danger.

"The circumstances that occurred as a result of your choice in the system that you set up … speaks volumes in my view of criminal neglect.

"I accept that there is a need to denounce this dangerous practice on behalf of the community.

"There is also an aspect of general deterrence that is in play here. There is the need to remind others of their parental responsibilities when undertaking the care of infants, particularly in such a dangerous place as a bath."

Kattenberg's four other children are in the care of their fathers.

Mother 'feels guilt and despair'

Kattenberg told the court she took full responsibility for her son's death. ( Facebook: Kandi Kattenberg )

Kattenberg's barrister Scott Geeves said as a single mother, his client had the pressures of looking after her children and hosting other family.

He said Kattenberg regretted her actions and continued to feel emotions of guilt and despair.

"She accepts roundly, and without reservation, that allowing a 10-year-old to supervise a nine-month-old child is unacceptable," Mr Geeves said.

"She accepts in a fulsome way her entire responsibility for not supervising Carlyle as she should have, not withstanding the pressures of the day.

"There was no intention of harming Carlyle whatsoever.

"Despite what took place on November 9, in all other respects, Carlyle was a fit and happy baby.

"She loved him and she still loves him."