Water Safety New Zealand general manager Alex Brunt said it was a concern that anyone might buy the product believing it would prevent children drowning. "You can't just have an alarm to mitigate pool fencing," Brunt said.
"If you've got a parent who's inside and is delayed getting to a child when the alarm goes off, to be falling back on your ability to perform CPR isn't something we deem appropriate."
The Fencing of Swimming Pools Act, enforced by local authorities, mandates fences for any time a pool is filled or partly filled with water.
Pak 'n Save parent company Foodstuffs said the alarm system should be used only in addition to other pool safety equipment and appropriate fencing. "This product is not a Foodstuffs Auckland-listed product. It is possible the odd store may stock this product but we are unable to confirm how many."
Chinese company Bestway Inflatables & Material Corp makes the product. Bestway said it shipped the items to New Zealand more than a year ago. An employee said the sensitivity of the alarm was adjustable to prevent false alarms by wind.
Brunt said new products arrived each summer that tested the boundaries of what was acceptable under the fencing act.
"You just have ones falling through the cracks."
He said spa pools were another problem - they should have a locked, hard cover capable of withstanding 25kg at its centre. Brunt said spa pools should also be registered with local authorities but retailers sometimes sold them without informing consumers of legal requirements.
Brunt said all retailers had a moral obligation to keep buyers adequately informed about legal and safety issues. He said some paddling pools were possibly problematic, too.
"A lot of people over summer have bought paddling pools which are a lot larger than your standard one.
"These big things coming in with filtration systems do pose a significant risk to infants ... it's probably something the public haven't considered that well," Brunt said.
Water Safety NZ figures showed 93 people died of drowning in New Zealand last year.
On average, five people drown in home pools each year.