All of the region's 17 beaches scored 100 per cent for water quality in the annual State of the Beaches report, making them the cleanest in NSW.

Environment and Climate Change Minister John Robertson said the Hunter's beaches were the cleanest they had ever been.

"Newcastle, Lake Macquarie and Port Stephens beaches have come out on top in the annual State of the Beaches report," he said,

"This is fantastic news for everyone planning to hit the beach this weekend to escape soaring summer temperatures.

"All along the Hunter coastline, from Zenith Beach in the north to Caves Beach in the south, water quality is as good as it gets.

"Burwood North and Burwood South beaches both improved this year and joined the list of NSW's cleanest swimming spots."

The study tested for faecal coliforms and enterococci and found that all ranked equal first for cleanliness.

In Sydney, only 29 of 35 beaches had perfect water quality, but that was still a huge improvement on nine years ago when only seven Sydney ocean beaches made the cut.

This year, 41 of the 59 harbour swimming sites in Sydney also had 100 per cent water quality.

Bondi Beach was found to have perfect water quality just 90 per cent of the time this year.

The only beach to fall below the 80 per cent mark was Malabar Beach in Sydney's east.

The Hunter topped the Illawarra, with 16 out of 18 perfect beaches.