A south-east Queensland water disinfection plant has become the first in Australia to be powered entirely by an off-grid, commercial-sized Tesla battery.

The Logan City Council's new water reservoir at Round Mountain, which has been built to cater for the growing community in the region's south, was constructed so far from the nearest power grid that it needed its own power source to be economically viable.

Logan Mayor Luke Smith said the Tesla battery, invented by technology billionaire Elon Musk, has saved ratepayers $1.9 million in power connection costs and would allow the reservoir to chlorinate water "off-grid".

"There was a need to have this reservoir, there was a need for it to be powered for its chlorination treatment however it was in an area where it was completely off the grid," Cr Smith said.

"We were concerned until demand increases, water stored in the network may age and not stay at the highest possible quality."

Cr Smith said it also meant the council did not need to build a sealed road to the facility because it could operate largely by itself.

The PowerPack will help the reservoir service 200,000 people when the region is developed. ( Supplied: Logan City Council )

The massive 95kWh Tesla PowerPack battery is the first to be installed in Australia, and comes amid a wave of support for solar-powered batteries among Australian households.

Three hundred and twenty-three solar panels have been installed on the roof of the Logan reservoir to collect sunlight to be stored in the battery.

The technology will allow the reservoir to provide safe drinking water residents south of Logan 24 hours a day and is expected to service 200,000 people when the region is fully developed.

"We've obviously been trialling it for the last few weeks and we're confident that it's going to work but what it will do is it will set a new standard, I think, globally but particularly what we're building in Logan," Cr Smith said.

"We've got a lot more [reservoirs] to build and we'll be looking at how we can use this innovation in sewerage treatment plants that we will have to build in the future."

The Logan PowerPack is a fraction of the size of the world's largest Tesla battery set to be built in South Australia in an attempt to make the state's grid more reliable.

In July, Tesla boss Elon Musk said the 100MW lithium battery in South Australia would be about three times the size of the next largest battery.