Perth least sustainable city: ACF

Perth has been ranked Australia's least sustainable city in a new index created by the Australian Conservation Foundation (ACF).

The Sustainable Cities Index tracks the progress of Australia's 20 largest cities across 15 indicators including air quality, ecological footprint, green buildings, water, biodiversity, health, density, wellbeing, transport, employment, climate change readiness, education, food production, public participation and household debt.

Perth was dragged down by recording the highest level of water use, car ownership, and ecological footprint per person.

The ACF estimates there are 641 private vehicles for every thousand people.

Darwin was the most sustainable.

Darwin topped the list, scoring well with clean air and strong biodiversity, but lost marks on health and preparedness for climate change.

It had the lowest unemployment rate at 1.89 per cent and household repayments were the lowest, with less than 23 per cent of household income spent on loan repayments.

ACF executive director Don Henry said the index was sure to ignite inter-city rivalries and get debate going.

"Australia's major cities consistently rate among the most liveable, but liveability is not the same as sustainability," Dr Henry said in a statement.

"In this federal election year it's up to our political leaders to prove they have the plans to deliver world class public transport systems, clean up Australia's vehicle fleet and make our cities truly sustainable."

Queensland had the most cities in the top 20.

The Sunshine Coast came in second, Brisbane third, Townsville fourth, the Gold Coast eighth and Toowoomba 11th.

The Sunshine Coast shares the top of the environmental performance basket with Brisbane and it was listed as having the best air quality.