The figure, based on the results of swimming pool barrier compliance certificate inspections in Wollongong this year, shows many pool owners will still have plenty of work to do if they are to adapt to the new pool safety regime when it is enforced from April 29 next year.

But the issue of who will do the enforcement is still contested, with several councils, including Wollongong, concerned about who will take responsibility for ensuring a non-compliant pool is upgraded.

Under the new NSW laws, all private pools must be registered with the local council, and recently built pools will need to be certified either by a council inspector or a private certifier. A house with a pool cannot be sold unless it has been certified.

Wollongong City Council has had 70 certificate applications lodged, a spokesman said, with the first inspection in each instance showing the barrier or fence did not comply.

Wollongong has three private pool certifiers listed on the Office of Local Government's website, while Shellharbour has one, and Kiama none.

Peter Burgess, of Illawarra Certifiers, said the main reason pools don't comply is that the fence or gate has not been properly maintained, often with the gate not securely on its own, as per the regulations.

"Several councils have done studies - they're all up there around that 90 per cent [non-compliance] figure," he said.

"Probably some of the main reasons are simple things like gates not closing, gates opening the wrong way."

Vegetation and other structures adjacent to the fence can often mean there are footholds allowing the fence to be climbed.

A fence must be 1.2m high, with 900mm between any horizontal sections, so children cannot climb up.

Pool barriers that form boundary fences have stricter restrictions and usually need to be 1.8m high.

The council spokesman said other common faults included the lack of resuscitation information posted near the pool, windows or doors allowing access directly from a house to the pool area, and incorrect fencing.

Certifier Ron Moore, of Building Certification Associates, said he did not find a 95 per cent non-compliance rate, but said the amount of inspections he had been called out to had declined since the State Government extended the deadline by 12 months to next April.

For more information see the Office of Local Government website www.olg.nsw.gov.au and follow the swimming pool links.