The use of Class A drugs are on the rise across New Zealand

The latest quarterly wastewater testing shows nationwide meth use has increased by 30 percent compared to last year's results.

Cocaine use rates have risen 50 percent.

More than 17 kilos of methamphetamine and 3 kilos of cocaine are used weekly on average.

Meth use alone is believed to be costing the country more than 19 million dollars a week in social harm.

Drug Detection Agency Chief Executive Glenn Dobson says cocaine has become much more popular here and Australia.

He says drug is like any commodity, with changing tastes and supply to meet the demand.