Sewage tests in Western Australia have revealed the state's citizens are using about two tonnes of methamphetamine each year with a street value of $2 billion.

Raw samples from three Perth treatment facilities were sent to the University of South Australia for analysis.

The initial 12-month samples revealed 31.6 kilograms of methamphetamine was consumed in the metropolitan area each week, or 1.6 tonnes annually.

The research was extended to Bunbury in January 2015. The area recorded the highest rate of all catchment areas recorded, with an average of 558 doses each week per 1,000 people, ABC News reported.


Perth averaged 344 doses per week, while Geraldton recorded an average of 314 doses.

"These tests provide us with a level of data that we have not previously had. It is scientifically proven, it is peer-reviewed and it is accurate," Assistant Police Commissioner Michelle Fyfe said.

Police Minister Liza Harvey said the data confirmed Perth has a methamphetamine problem.

"We've seen spikes at certain points - when there's been seizures made we see a dip in usage rates - and so we can determine if we're actually interrupting the supply chain," she said.

Similar research covering nearly 25 million people in 42 European cities has revealed cocaine use is heaviest in London, Antwerp, Amsterdam and Zurich.

Cocaine and ecstasy use spikes on weekends, while the use of methamphetamine and cannabis is more evenly distributed throughout the week.

- Herald online