The National Capital Authority has challenged engineers to restore the historic fountains at Old Parliament House, which have been left to ruin.

The federation fountains in Parkes Place have been criticised as a dangerous blight on the parliamentary vista, which do not justify an estimated $9 million repair bill.

But the NCA believes it could revive the fountains and cut the authority's water bill by millions in the long-term.

NCA chief executive Helen Badger is hopeful the fountains may be restored as part of a larger multimillion dollar overhaul of water infrastructure.

"We hate that the fountains look the way they do and that they have not been operating at full capacity for 10 years," she said.

"They have been abandoned for the last five years due to costs and safety compliance issues."

The NCA has called on engineers to draft a new water infrastructure system that would allow the authority to triple the amount of water currently taken from Lake Burley Griffin.

"We have challenged engineers to see if they can find a design that pumps water from the lake to the fountain, and maybe use it as a storage facility as part of the new infrastructure," she said.

"We don't know how they will do it, but we have challenged them to come up with a solution so we can get the fountains presentable once again."

Approval to take 623,000 kilolitres of water a year the lake has already been granted by Icon Water, but the NCA does not have irrigation systems capable of doing the job.

Instead, the parliament triangle has been irrigated by potable water purchased from Icon Water at a significant cost.

"At the moment the triangle is currently irrigated using potable water and that is not efficient and is very expensive and we would like to use lake water in the same way the golf club does," Ms Badger said.

Since 2000 the NCA has used between 250,000 and 750,000 kilolitres for irrigation at a cost ranging from $2.64 to $5.29 per kilolitre.

An audit report on the fountains, prepared by Storm Consulting and presented to the NCA last year, found the fountains were dangerous and in need of specialist care.

The report found the fountains had leaked at an unacceptable rate due to broken hydraulic pipes, cracks in the walls and failed fittings, with access to pumps deemed dangerous to workers.

"These water displays are a prestigious embellishment for the parliamentary zone," the report said. "They should be a prime attraction and provide a central meeting place for many to enjoy."

"Future upgrades should use only quality materials and have the highest standards of workmanship."

Access to the fountain pump rooms is reportedly dangerous and must be improved before restoration of the fountains can be completed.

"The electrical installations in the plant rooms have electrical components exposed and this is a dangerous state that should be made safe," the report said.

The report also said repairs to the fountain in 1999 were inadequate and failed to address many structural failings.

"The fountain ponds show clear signs of floor cracking where hydraulic pipes have been laid under the concrete topping," the report said.

"In any future upgrade the existing hydraulics and electricals will need to be removed and upgraded."

If the plan is successful, the capital's fountains could all be working for the first-time in years.

Lake Burley Griffin's Captain Cook memorial jet will soon get a major upgrade after a forgettable year that included a pump system failure that had knocked it out of action since June.

The jet is expected to operate at its full height of 147 metres once the scheduled maintenance works and restoration are completed next year.