Scientists testing the country's wastewater for drugs want to extend their search to evidence of synthetic drugs but say they first need to understand how they break down.
Levels of methamphetamine, cocaine, heroin, ecstacy and fentanyl are being looked at in about 80 percent of the country's wastewater systems after successful pilot programmes.
Police Commissioner Mike Bush has said the testing was crucial to build a better picture of illicit drug use across the country.
But there has been concern about how detailed the data collected is.
ESR chief executive Keith McLea told Nine to Noon wastewater testing was across large communities.
Data from individual houses or streets was not being collected, he said.
While it was technically possible, it was very expensive, and was not something they had even discussed.
"If you were sampling in much finer detail, I'm sure there would be privacy issues, but because the sampling we're doing is very aggregated those sort of issues shouldn't arise."
Wastewater is not currently being tested for synthetic cannabis, which has hospitalised people and caused deaths across the country.
But Mr McLea said that was not because the desire was not there.
He said scientists are researching how new synthetic drugs change in the wastewater system.
"What we're testing for is more than just the drug itself," he said.
"If you smoke it and you excrete it, you're actually dealing with metabolites."
"[You have to] look at what the metabolites are [also] look at how stable they are in the wastewater environment."
ESR scientist Andrew Chappell said information from wastewater can also highlight people's exposure to other chemicals, such as pesticides present in food and phthalate plasticisers from food packaging.
"People are also looking at community-wide exposure to endocrine-disrupting chemicals in personal care products.
"Those are chemicals that affect the hormone system."
Police are funding the project and working with ESR, Customs and the Ministry of Health.