Illicit drug consumption has dropped in Australia but cost of living pressures have had no impact on demand, with the country's most popular drug also the most expensive.

More than 14 tonnes of methylamphetamine, cocaine, heroin and MDMA were detected in wastewater systems between August 2021 and 2022, according to the Australian Criminal Intelligence Commission's latest wastewater snapshot.

That's a reduction of about 10 per cent compared to last year but the commission attributes the fall to drug busts rather than financial pressures.

"Those drugs had an estimated street value of $10 billion, which is a real concern at a time when household budgets across the country were stretched," the commission's principal drug advisor Shane Neilson told AAP.

More than 83 per cent of that haul was methylamphetamine, which can be turned into highly addictive drugs ice and speed.

Opioids are a growing concern with heroin the second most used illicit drug nationally, and consumption of oxycodone and fentanyl also on the rise.

MDMA usage fell 41 per cent and cocaine has dropped by almost one third.

"The median national street price of a cocaine 'deal' is less than the price for a crystal methylamphetamine 'deal', so price does not appear to be a factor in the decreased consumption of cocaine," according to the report.

It's estimated 600 kilograms of cocaine were seized in 2022, which was about double the amount thought to have been ingested.

European crime gangs have reduced the amount of MDMA they produce in favour of methylamphetamine.

Mr Neilson is optimistic the opioid crisis in North America may not reach our shores.

While the medications can be prescribed for certain medical conditions, they are frequently misused.

"There's organised crime involvement in that, at a level there's people in various professions that are involved in diversion of products to the illicit market, which of course was a huge problem in the United States with fentanyl and obviously codeine," Mr Neilson told AAP.

"There's also a situation where individuals simply take the drugs they receive lawfully, but use them illicitly either in whole or in part."

Mr Neilson believes part of the reason why ice is so popular is because addicted users can easily access it due to local manufacturing and imports.

Data for the report was collected in August and October 2022 from 58 wastewater plants across Australia, covering about 14 million people.

Ketamine and cannabis are also growing in popularity.

Nicotine and alcohol remain the most commonly used substances and consumption is relatively stable.

December is the most popular time to consume drugs, believed to be due to a combination of organised crime groups ramping up supply during party season and more opportunities for people to take them.