Water pipeline $15m upgrade

About 5.5 billion litres of water, or more than 30,000 rainwater tanks, is lost annually as a result of leaks.

A significant proportion of the spending will be used to plug holes in the ageing 85-kilometre Chichester Trunk Gravity Main pipeline.

The 90-year-old pipeline, which runs between North Lambton reservoir and Chichester Dam, is responsible for almost 70 per cent of all water main failures on the network.

A further $15.2 million will be spent replacing sections of pipeline over the next four years. Hunter Water has already spent $17.5 million on the project in the past four years.

A 7.5-kilometre stretch between Tarro and Shortland was buried in 2009.

About 75 per cent of the original pipeline will have been replaced when the latest round of works have been completed.

"A decision was made almost 100 years ago to lay the pipeline above ground as part of the construction of the Chichester Dam," Hunter Water chief operating officer Darren Cleary said.

"The consequence of laying the pipe above ground is that it is particularly susceptible to leaks caused by temperature-induced expansion and contraction."

The original pipe was built from cast iron with lead joints.

Numerous cattle died after eating flaking lead from the old structure in 2010.

The new sections of pipeline are made of steel with welded joints and rubber-ringed joints.

A maintenance crew, similar to one that works on the Sydney Harbour Bridge, is assigned to maintaining and repairing the giant structure.

The crew repaired a leak that was detected at Brandy Hill, near Seaham yesterday.

"The pipeline itself is hugely important to guaranteeing Newcastle's drinking supply with around 35 per cent of total water travelling through it each day," Mr Cleary said.

"It is reaching the point where maintenance alone is not sufficient."

The utility recorded an overall 14.4 per cent increase in breakages last year.