Australian taxpayers will be billed an estimated $115,000 for Prince Harry's month-long army secondment – including $1000 for bottled water and Gatorade.

The 30-year-old barely appeared in public during his stay in Australia from April 6 to May 9, but the public is still expected to foot the bill.

Prince Harry made only one public appearance during his visit to Australia. Credit:Gregg Porteous

While Defence has not yet tallied the total cost of the stay, Fairfax Media has obtained documents containing the army's preliminary cost estimates.

The "proposal for expenditure" document lists the estimated total cost of the stay as $115,940.