Having paid the bill, the residents say their complaint is only partly about the money, and say the authorities should be doing more to combat water losses at a time of extreme drought.

Col Parkins, representing the four households at Ashley Villas in Kokera Street, Wallsend, said they rang Hunter Water on August 29 to report water running into the gutter at the front of their property.

"We asked for someone to come out but the person on the phone said if it was coming from the right-hand side of the driveway it was a stormwater drain and not their responsibility because the water meter and pipes were on the other side," Mr Parkins said.

"They suggested we ring Newcastle City Council. Someone from the council came out a few days later and said it was coming from a natural spring. This surprised us, but the council said they were quite common where we were.

"The leak continued, and then we received the $400 excess water charge from Hunter Water on November 25, which showed what we'd told them in the first place, that it was a leaking water pipe."

Mr Parkins said a specialist detection service found the leak, in a pipe under the concrete driveway, on December 9, but the holiday season meant the plumber wouldn't be able to start the work until the 14^th of this month at the earliest. To minimise water losses, they'd been turning the mains off nightly between 9pm and 7am.

Mr Parkins said the residents understood that Hunter Water's responsibility ended at the water meter, but the leak had continued as long as it had because of the responses from Hunter Water and the council.

Responding, a Hunter Water spokesperson said the organisation took leakage very seriously, especially as the region was in severe drought.

FURTHER READING:

The spokesperson said Hunter Water could not discuss individual accounts without the written permission of the customers.

In general terms, Hunter Water regarded "water security as a shared concern" between it and its customers.

"Although the property owner is responsible for the security of the water supply once it passes through the meter, Hunter Water works to ensure owners remain aware of their responsibility, and that they have the right knowledge to identify leaks as early as possible to ensure water losses are minimised," Hunter Water says.

Hunter Water also offers an "undetected leak rebate" for 50 per cent of leak-related water charges was available to "eligible customers".

The Herald notes, however, that the application form says "an undetected leak is where there is no visible sign of water loss". It says applications "will be denied" when "water is found seeping, spraying, pooling, bubbling, running, flowing, gushing etc".

Hunter Water's spokesperson said that falling dam levels had led the organisation to lift its "active leak detection work" by 20 per cent to survey 120 kilometres of network a week.

"Hunter Water is also trialling new technologies to help detect hidden leaks," the spokesperson said.

"This includes a digital innovation trial in parts of Lake Macquarie and Maitland using Internet of Things (IoT) devices with data science and acoustic monitoring technology to monitor water pressure and flow.

"Later this month we also plan to commence trialling new LiDAR technology, which uses drones at night to improve leak detection."

LiDAR is the name given to a new digital survey method, and is short for Light Detection and Ranging or Light Imaging, Detection and Ranging.

Wikipedia says LiDAR measures distance to a target by illuminating it with laser light and measuring the reflected light with a sensor. Differences in laser return times and wavelengths are then used to make digital 3-D pictures of the target.

LiDAR is increasingly used to make high-resolution maps, and it is also used in control and navigation for some driverless car technologies.

While you're with us, did you know the Newcastle Herald offers breaking news alerts, daily email newsletters and more? Keep up to date with all the local news - sign up here