Drowning has claimed a third life in a matter of two days.

A Perth toddler has died in hospital after drowning in a backyard pool on New Year's Day.

The 23-month-old toddler died several days after she was found partially submerged and unconscious in the family pool's skimmer box at about 11am on New Year's Day.

A Princess Margaret Hospital spokeswoman confirmed with News.com.au the little girl was rushed to the hospital on New Year's Day but died Thursday night.

The Perth toddler's death is the third such tragedy in merely 48 hours. A seven-year-old boy also drowned on Thursday in a dam on his family's property in Katanning, 270km south-east of Perth, and a nine-month-old baby girl drowned in a bathtub in rural Victoria.

The tragedies prompted Royal Life Saving Society WA spokeswoman Lauren Nimmo to urge parents to be more careful in supervising their children near the water.

"With temperatures soaring, people are participating a lot more in aquatic activity, and particularly with children close supervision at all times when they're around the water is the best way to prevent a drowning death from occurring," she said.

Also on Thursday, lifeguards saved a 4-year-old boy found lying unconscious on the bottom of a public pool. The toddler was not breathing when he was found by staff from the Camden swimming pool, in southwest Sydney.

The little boy was rushed to hospital after CPR and is expected to make a full recovery, News.com.au reported.