The Curious Case of Benjamin Button star headed to The Wharf to lend her support to the Sydney Theatre Company's latest green initiative, which captures rainwater from the roof and stores it to service the building's showers and toilets.

Blanchett and her husband Andrew Upton, who both serve as artistic directors at the Sydney Theatre Company, were both on hand for the big unveiling and she commended locals for taking action to save one of the world's most precious resources.

She said, ""We're all pleased to bring this innovative engineering technology into our creative lives today and indeed to be a showcase of how such systems can function to great economic and societal benefit.

""The entire project has been made possible through a unique collaboration with private philanthropists, corporate and government support, both state and federal, who really understand the incredible opportunity that greening this amazing arts precinct represents not only for the organisations down here but for the city of Sydney and the state... So, have a shower or use the loos (toilets).""