Five pre-school children have drowned in New Zealand so far this year, three of them in August.
Water Safety New Zealand general manager Matt Claridge says to have 3 deaths of pre-school children during one winter month is alarming, given the total annual average is 10.
The deaths have prompted safety experts to urge parents to better supervise their children, and introduce them to water safety from an early age.
Mr Claridge says there will always be barriers to children learning to swim, including cost, but they need to develop water confidence from a young age.
SafeKids director Sue Weaver says adults need to directly supervise children in the water because they drown quickly and silently. The organisation is running a two-year campaign on water safety.
So far this year 69 people have drowned, one fewer than recorded at the same time last year.