Alcohol or drug abuse by a parent would not necessarily 'trigger' the removal of a child from their biological family, a parliamentary committee investigating Families SA has heard.
Department for Education and Child Development chief executive Tony Harrison told the committee while he would not want any parent abusing alcohol or drugs, it was not realistic.
"Illicit drugs or excessive use of alcohol by itself would not be a determinant whether we would leave a child in a biological family," he said.
"So I wouldn't advocate to the committee that there should be a trigger if we were to identify the use of illicit substances or alcohol to excess that that becomes the only factor we would take into consideration for removal of that child from a family unit."
Last week, the coroner investigating the death of four-year-old Chloe Valentine in Adelaide was told Families SA approved a plan to let her mother use drugs provided a "sober adult" cared for the girl.
Mr Harrison said the removal of a child by Families SA was a 'major decision' and had the potential to cause a child further harm.
"Removing a child can literally cause more detrimental harm in the form of abuse or neglect of that child because of the potential difficulties of placing it in a nurturing, caring loving environment outside of that biological family," he said.
"I'd suggest strongly if we were to take that approach we wouldn't have 2,600 children in the care of the minister we would have many many, many more."
Premier Jay Weatherill agreed that sometimes removing a child from a home does more harm than good.
"There are not enough resources in the world neccessary to be able to investigate child protection notifications that occur in one in four families," he said.
"It is just simply impossible to devote those resources and it is undesirable we'd have 20,000 kids in our care not 2,000."
Families SA needs to 'crack down' on drug-abusing parents
Mr Harrison told the committee he believed Families SA got its decisions on removing children right most of the time.
However, Family First MP Dennis Hood said Families SA needed to crack down on parents who used drugs.
"I think the public can be forgiven for thinking Families SA almost condones the use of these substances," Mr Hood said.
"It seems that there isn't any clarity about what to do, what are the triggers for action to be taken.
"I mean for me it's relatively simple. If parents are using things like methamphetamine on a regular basis or even a semi regular basis certainly if they're a heroin user, something at that end of the scale, then their ability to look after a child is clearly lessened.
"If somebody's using illicit substances then we really have to ask: are they suitable to look after their children?"