Police are about to start testing wastewater in Auckland and Christchurch, to get a better idea of drug use in the community.
Similar testing in Perth has found 31.6kg of meth was consumed in the city area each week, that's 1.6 tonnes a year.
Now police want to do the same here.
The testing, which will look for methamphetamine, cocaine, heroin, alpha PVP, MDMA and Creatinine, will take place in Christchurch and Auckland's Rosedale treatment plants.
Police say the results, which can't be traced to individuals, will improve their understating of drug use in the population.
"Accurate information on drug use is essential if associated harms are to be addressed effectively," said Assistant Commissioner Bill Searle.
Mr Searle said the results will also inform treatment and enforcement strategies, allow comparison with international data, measure the effectiveness of education and enforcement and provide intelligence data.
"International studies of wastewater have shown distinct temporal and geographic patterns of drug use."
Mr Searle said in Perth police were able to measure things like peak days for use and the effects big seizures have on their usage rates.
The testing will be undertaken by the Institute of Environmental Science and Research for one week each month for a year.
ESR scientist Andrew Chappell says "this is an exciting new area of research that we are proud to work together with the Police on".
Wastewater testing and analysis is a means of quick and accurate assessment of prevalence of drug use in a community.