Four-year-old Charli Squires spent last year petrified of the water after he almost drowned in the family pool.
Big brother Kyle saved the then two-year-old in 2012 with quick thinking and CPR, and later received a NSW Ambulance award for courage for his efforts.
Charli's fear of the water was conquered only when he started one-on-one lessons at Nippers 2 Flippers in Figtree.
Swim school owner Anita Peck, who took Charli for his first lesson, said it was important for him to trust her and the other instructors.
"The way you come across is so important," she said.
"You must reassure them you are not going to let them go."
Parents Jayson and Emily Squires said Charli's attitude and fear of the water changed after five lessons.
"It was almost overnight that his confidence came back," Mr Squires said.
"They built up trust with him and he knew that they weren't going to leave him."
Mrs Squires said it was the school's passion for seeing children succeed that worked.
"Finding a swim school where your child is comfortable is so important," she said.
"We could have given up, but it was important we pursued lessons for Charli."
Mr Squires said he didn't know how to thank Ms Peck.
"Our whole life is the beach and the water, and to now know it will go forward is amazing."