Up to a quarter of workers on building sites in Christchurch are failing drug tests, and the numbers are rising sharply.
The increase is being blamed on the alarming rise of the availability of methamphetamine.
Karen Woolf from Triex, the company that drug tests workers, says they're seeing some alaming results on construction sites across Christchurch.
"When we do random testings, we can get as much as 20 to 25 percent with a non-negative test," Ms Woolf told ONE News.
The New Zealand Drug Detection agency says overall 7.5 per cent of people in the construction sector are failing drug tests in Canterbury.
The number is higher than the national average of just over six per cent.
Ms Woolf says cannabinoids is usually why workers fail drug tests, but an increasing amount are now failing because of methamphetamines.
She says a year ago she'd barely have seen a single failed test due to methamphetamine, but now it's not uncommon.
That anecdotal evidence is backed up by the latest Massey University study into illegal drug use which showed over a period of two years the availability of methamphetamine in Christchurch has expanded.
This increase has prompted Workplace New Zealand to launch drug and alcohol workshops for local companies.