California dry days, that is.

As the 39 million residents of the US's most populous state enter their fourth year of severe drought, the business's water recycling appliance cannot go on sale soon enough.

Craig Richmond and his two colleagues' start-up, Nexus eWater, got the $2.1 million in backing they needed late last year and their NexTreater product could be on the market within weeks. It received US certification this month.

The company has said it is the world's first practical energy and greywater recycler for homes, promising to reduce annual water and wastewater usage by up to 40 per cent and electric energy usage by 12 per cent.

Mr Richmond said the team would be pushing for the appliance – which looks like a hot-water system – to be embraced by Californian builders.

"The motivation for the builder is that in California a number of cities are saying they may cease approving home production due to the drought – the pressure is on the builder to come up with better water solutions," he said.

The NexTreater unit is set to retail for about $US3000 ($3800), but with installation and the two tanks required it would be about $US5000-$US7000 ($6400-$9000). Mr Richmond said homeowners would likely break even within three to five years.

And while the company now has two offices in California and one in Alabama in addition to its Fyshwick R&D centre, its founders remain grateful for an early $50,000 grant under the ACT government's Innovation Connect program in 2012.

"It was critical to us getting where we are today," Mr Richmond said.

He said a roll-out in Australia would be dependent on US success.

California Governor Edmund Brown Jnr declared a drought state of emergency in January and earlier this month announced a $US1-billion emergency drought package.