His phone was charging five metres away from him, but he couldn't reach it.
His late night cries to his neighbours for help at about 10.30pm also went unanswered.
So with few other options available, the retired broadcaster took to his computer which was right in front of him.
"I thought I must be able to do something so I started emailing the world basically."
He sent about a dozen emails to St John, Police, friends and even his landlord desperately hoping someone might still be awake and checking their emails.
"I was just thinking who might possibly be checking their emails at 11pm on a Saturday night."
Despite not being much of a social media user, he then remembered about the local Waiheke Facebook page and put out an SOS there describing his predicament and giving his address.
"I need URGENT help. This is not a joke," the post said. "I have had an accident but am not near the phone. My leg has twisted, I think my hip has dislocated, and I cannot get to the door or phone."
Within 10 minutes of his virtual cry for help, he heard what he described as "voices in the night calling his name".
"It was really fast... that's the thing I suppose - there were people doing things on the page. "
A resident who is a member on the page had been scrolling through Facebook and saw his post about 11.30pm. She called Waru's neighbour and local community board member Kylee Matthews who was one of the people he had attempted to tag in his post.
Matthews who had just gone to bed missed her call, but then decided to call her back.
After calling out to Waru, Matthews' partner then smashed a window to get to him and open the locked door.
It was a relatively easy process to get him to the ferry from there, she said.
Matthews said she was so pleased she had returned her friend's late night call because Waru could have made his injury worse by trying to move.
Matthews then called St John and the local Waiheke Island ambulance crew arrived and gave him some pain relief before taking him down to the wharf.
An Auckland-based ambulance crew met him and transported him over to the city on the last ferry for the night.
After being treated at Auckland Hospital, Waru was home the next afternoon and is feeling extremely grateful to the Waiheke community.
He said it showed how the community rallied together when someone needed help. He had also heard he was the talk of the island the next day with people inquiring to his neighbour about how he was doing.
"At least the community page works," he said.