"We're just in shock to be honest. I dropped them off at the airport and she was joking around, excited as anything to be going to Samoa for the first time.
"I just can't believe it."
Neemia Tialata posted on his Facebook page earlier today "Still coming to terms with the drowning of my dear liddle cousin Tai Pilitati.... I know your happy in heaven now with your daddy RIP lots of Love and Prayers"
Six people were rescued from the floodwaters and taken to Moto'otua hospital, but all six have now been discharged.
The holidaying family were in the capital of Apia, when they were carried down the river.
A hospital spokeswoman confirmed that the other people taken for treatment were in a stable condition and treated as outpatients.
A boy who had been sitting near the riverbank told the Samoa Observer newspaper he was shocked at what he saw when the tragedy struck.
"I thought it was a doll ... it wasn't until I walked closer to the rocks that I saw it was a person.''
The boy called to another person nearby for help, and they pulled the person from the water, but it was too late.
The man who helped recover the body told the newspaper: "She was already dead when I got to her. I called out to my friend to call the police. She looked young - about 19. It was so sad.''
A doctor at the hospital confirmed the family were holidaying from New Zealand.
