"He's been very good at hiding he's got issues, other than when these instances have exploded," Kowalski told SEN radio today. "That's my biggest concern, that he's lived with this for so long and he's covered it up for so long.
"When yesterday happened, I must admit I wasn't totally surprised, because it was more a matter of 'when' not 'if'."
Hackett is reportedly being treated in hospital following his arrest, with brother Craig describing the retired swimming great as a danger to himself and the community.
Police were called to his parents' Mermaid Waters home earlier in the day, following reports of a disturbance. Father Nev said calling police to help calm his son down was the only option available to him, after he became agitated and verbally abusive.
Hackett was filmed by media slumped and handcuffed in the back of a police car, as he was taken to the Southport watch house, before he was released without charge.
Kowalski hoped Hackett would receive support following the incident, but did not know how under-resourced swimmers' welfare support workers could support Hackett.
"When it gets to Grant's situation, I just don't know what more the sport could have possibly done," Kowalski said.
"The resources and the money, we just don't have them. You rely on people talking, and seeking help and advice, and going to someone, but it's a really taboo subject still.
"[He needs] some tough love and [to] go to a place that won't let him check out of rehab early.
"Hopefully, he can look in the mirror now and say, 'right, its now or never'."
Hackett has struggled with addiction and other personal issues, since his retirement after the 2008 Beijing Games.
