But it means the iconic water fountain will be out of action until the first half of next year with work due to begin in October.

The National Capital Authority has fast-forwarded a program of scheduled maintenance works to coincide with the restoration.

Once complete, the jet will operate at its full height of 147 metres for the first time in several years.

The fountain has been marred by problems this year and out of action since June due to a secondary fault. The fault resulted from an unexpected failure of its pumping system earlier this year.

Executive director Helen Badger said the "vital" double upgrade would get the jet working sooner.

"These works will mark the first major overhaul of the iconic jet in 20 years," she said.

"The last extensive upgrade after its 1970 inauguration was in 1995, making this project vital in preserving this national asset.

"This project will address key electrical, mechanical, hydraulic and fire service works all at the one time and will ensure the jet complies with current [health and safety] standards.

"We are confident that these works will assure the long-term future of the jet so that it remains a landmark attraction in the national capital."

The NCA was reviewing tenders for the works and expected to choose a contractor in the coming weeks, before developing a schedule for staged works.