Wastewater flushed down drains and toilets by 80 per cent of the country will be examined for evidence of methamphetamine and other illegal drugs.
Signs of cannabis use will also be tested in Northland and Auckland under an expanded testing regime announced today by the police.
The police said wastewater testing for drugs would be rolled out across New Zealand, with the expansion of the current pilot programme of the police and ESR (Institute of Environmental Science and Research).
The main aim is to provide information for drug prevention and treatment strategies.
Testing will be extended to 38 localities across the 12 Police districts this month and will capture 80 per cent of the population.
Police Commissioner Mike Bush said wastewater testing was crucial to the force's understanding of drug consumption in our communities.
"Expanding the programme to regional New Zealand and other major centres will help us continue to build a better picture of the prevalence of illicit drug use in New Zealand communities as well as the subsequent social harm."
Wastewater testing has been conducted by ESR at three locations – Rosedale in Auckland, Christchurch and Whāngarei since 2016.
Analysis of samples from these sites has revealed extensive and diverse patterns of drug use, and has significantly enhanced understanding around the demand and supply of illicit drugs and the impact on individual communities where testing was undertaken.
"Over the past 18 months, 1.5kg of methamphetamine was estimated to have been consumed on average each week across the three test sites.
This translates to an estimated $2 million a week in social harm.
"Expanding the number of sample locations will help us identify differences in drug use between geographic regions and will act as an early warning system for emerging risks," says Bush.
ESR chief executive Keith McLea says the organisation has extensive expertise in the science of wastewater testing.
"The pilot project provided real-time information about drug use patterns in the wider population which is proving invaluable in keeping communities safe. We highly value our partnership with Police and look forward to the national roll out."
The drugs currently tested for are: methamphetamine, cocaine, heroin, MDMA and Fentanyl.
Cannabis testing will be introduced in Northland and across Auckland/Tāmaki Makaurau, and checks for ephedrine/pseudoephedrine will be introduced at all sites as part of the rollout.
Results from the new testing sites will help inform prevention and treatment strategies, allow comparison with international data and measure the effectiveness of education and enforcement.
The four Auckland/Tāmaki Makaurau sites began testing on October 1 with the rest of the country's sites expected to be testing by the end of the month.