The coroner who investigated his death has called for greater safety campaigns, pool inspections and laws for fence non-compliance in Tasmania.
The island state lags behind the rest of Australia in oversight of pool safety standards, advocacy body Royal Life Saving says.
On November 7, 2020, the boy was left in the lounge room of the house at Bridgewater in northern Hobart when his mother went to the bathroom.
She called out his name periodically to check he was nearby but after some time received no response.
The woman and the boy's step-father started searching down the street where he often used to run.
Shortly afterwards she found him face down in the above-ground pool, which the couple had set up only weeks earlier after buying it online.
"(His) death tragically occurred ... namely (because of) a lack of parental supervision and a lack of appropriate fencing," coroner Robert Webster said.
"The risk ... was heightened by the fact the front door was unlocked.
"Given the absence of pool fencing (it) meant that once he was not supervised he had unimpeded access to the pool."
The couple said they planned to buy a fence from Bunnings after their next pay day.
Mr Webster called on Tasmania's government to follow NSW's lead and consider similar laws making it a crime to have a pool without a child-proof barrier or fence.
He also recommended all councils implement a program to check pools for fence compliance, and also called for an annual education program prior to summer.
Pools in all states and territories are covered by Australian standards, which are voluntary unless there are laws imposing penalties.
Royal Life Saving general manager Craig Roberts said there were no such penalties in Tasmania and the state trailed others in pool oversight.
"Tasmania is the only (jurisdiction) where pool registrations and regular inspections aren't required," he said.
The Brighton Council, which includes Bridgewater, undertakes random inspections of pools for compliance with standards but was not aware of the pool where the boy drowned.
A council representative told the coroner it had no issues with his report.
The state government has been contacted for comment.
The boy, described as a "good climber", had used the pool twice before he died and had not had any swimming lessons.
From July 2022 to June 2023, 281 people drowned in Australia - 29 of those in swimming pools including six children aged four or under.
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