According to one parent from the Jameah Academy, the 11-year-old fell from one of the boats when it hit a rock.
Treacy, 46, blamed park bosses for failing to ensure the ride was safe, and said yesterday's tragedy was an "accident waiting to happen".
It emerged today that Evha died on what should have been her final ride before going home.
One of her friends told the Telegraph the 11-year-old had almost missed the trip because she did not have suitable clothing and had to borrow some from her school at the last moment.
The girl added: "It meant she could go with everyone else. It's really sad. She was really nice".
Zainab Mohammad, 26, whose 16-year-old sister Summayyah attends the Jameah Girls Academy, said: "This girl's family are in total shock. I dread to think what they are feeling at the moment. They are grieving now. Everyone is. My sister came back from the trip really upset about it. She hasn't been able to talk properly about it."
Staffordshire Police said: "Evha sadly died after falling from a water ride at the theme park. She was recovered from the water and received advanced life support from ambulance crews before she was flown to Birmingham Children's Hospital where she later passed away."
Throughout the day a steady stream of mourners made their way to Evha's home, near Leicester's Golden Mile and a 10 minute drive from the school.
Family members, friends and teachers from the academy, along with grieving classmates, arrived at the modern terraced house to comfort the girl's distraught mother.
Eva's elder brother, a student at Loughborough University, was understood to be with father Muhammed Islam and mother Musammath Naha yesterday.
Islam is understood to have worked as a waiter in the Watford area before the family moved to Leicester.
In a statement, Evha's family, originally from Bangladesh, said: "Yesterday our world was torn apart by the news that our daughter and sister Evha, had lost her life in tragic circumstances, following a school trip to Drayton Manor Park.
"Evha was a beautiful little girl who was full of love and always smiling.
"Words cannot describe the pain and loss we feel, we are devastated that we will not see our beautiful little girl again.
"We ask that you allow us to grieve in private and deal with our loss as a family."
According to one parent from the Jameah Academy, the 11-year-old fell from one of the boats when it hit a rock.
She told the Mail Online: "When the girl got up to change seats just then it hit a rock and she got knocked out of the boat and fell in the water and the water currents dragged her in."
The parent said the girl disappeared from view after falling from the ride.
Treacy said she raised her concerns about the safety of the ride with a manager following her son's experience.
She added: "I just can't help thinking that if the park managers had listened to me more that little girl would still be alive. In the end that tragedy was an accident waiting to happen."
