"It is very timely to remind ourselves of the absolute importance of constant vigilance and attention to water safety, to ensure that the summer times remain happy time for our children," RCH director of trauma services Professor Warwick Teague said.
"In the last four days we've been faced with the terrible realities of the dangers that water plays for children."
Four children were admitted to the RCH in the last four days with "devastating injuries" sustained in or around the water on Boxing Day.
"Yesterday, a seven-year-old child was swimming in a backyard pool and drowned after a period of approximately 30 seconds underwater," Prof. Teague said.
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"It is important to recognize that this child was an able swimmer, this child had attended swimming lessons and was being supervised by an adult at the time of the incident," he said.
The RCH's main advice is children in the water are under constant adult supervision.
"Children under the age of five need at all times to be within arm's reach. Children under the age of 10 need at all times to be within our line of sight and 'at all times' means exactly that," Prof. Teague said.
"Unfortunately, children can drown in less than 20 seconds."
He added children should also have restricted access to water to help increase awareness of danger levels.