Mr Brackfield said because the New Zealand notes were made of plastic they could go through a complete wash and still be useable. He thought once the clump of paper-based US notes had dried out they also could be used.
Thanks to radio-frequency identification scanning technology the money was able to be traced back to the Sudima Hotel.
The laundry, which processes 20 tonne of washing a week, has all its laundry chipped and scans every item in and out.
Hotel guests, who were on their way to Wellington, had reported the money as missing the previous evening. The freshly cleaned cash has been returned to them. Sudima Hotel general manager Atalo de la Rocha said other things had been left behind at the hotel, but "this is the first time we've had money left in the sheets".