The NSW Local Government Minister, Don Page, says he's concerned up to half of the state's 130,000 swimming pool and outdoor spa owners are yet to sign up to the Swimming Pools Register.

Registration opened in late April for the register.

Owners have until next Tuesday to add their backyard pool or spa to the list.

Minister Page says an average of six children drown each year in backyard pools.

He says dozens more are admitted to hospital, many with permanent brain injury.

Don Page says the onus is on owners to complete a checklist for their pool, as part of the registration process.

"When you go online to register your pool you will be asked a series of questions and they will be questions like, 'Does the gate self-close?; Is the barrier at least 1.2m high? Are there any problems with the barrier that a child could get through?'," he said.

"The aim is so people will actually become more aware of what the regulations are in relation to their pool."

Minister Page says fines are being contemplated for those who don't sign up.

"There is a penalty fine of $220, and if you choose to contest that in a court, then the magistrate can impose a fine of up to $2,200," he said.

"So, I'd encourage people to go online and to register their pool, it's a pretty simple process, it only takes a couple of minutes, and then you're done in terms of meeting the requirements."