It will be the second time the festival has trialled pill testing in Canberra, after last year's trial was declared a success. The trials in the national capital are the only ones to have so far been held at an Australian music festival.

The trial comes after five young people aged 19 to 23 died at festivals in NSW alone from September to January, prompting a NSW coronial investigation.

The STA-SAFE consortium, which will run the trial, said the Groovin the Moo pilot would be significantly bigger than the first. There would be some changes based on lessons learned from last year, but the testing regime and technology would be the same.

The consortium’s Gino Vumbaca said there would probably be two machines this year, instead of one, with more staff. He expected substantially more festival-goers would have their pills tested as a result of the publicity of recent months. He expected that to mean a much bigger sample size of pills and pill-takers for the evaluation.

“It will be bigger because obviously now we have approval well in advance of the pilot, so we can prepare a lot more and there will be a fair bit more promotion about what we’re doing,” he said.

“… We expect lot more people to come forward and we expect that will result in lot more people not consuming drugs or moderating what they’re about to consume.”

People having pills tested would still be told the told the safest way was not to take the pill, regardless of contents, Mr Vumbaca said. But people in the tent had already “run the gauntlet” of getting through security with their pills, so were committed to using the drug, making the pill-testing trial “the last line of information and potential defence against any adverse reactions", he said.

This year, the consortium would not do its own evaluation but have a team from the Australian National University in the tent, recording data and reviewing the pilot.

The pilot would build on the first and “add to the evidence base”, he said commending the ACT for being the only state or territory prepared to allow pill testing, despite the consortium offering free services around the country.

Dr David Caldicott, who was set to appear on ABC's Q&A; on Monday night to discuss pill testing among other issues, said he applauds the decision.

"I think it's based on the evidence and the results that we were able to provide the last time [the trial happened]," Mr Caldicott said.

"At a personal level, it's gratifying to be living in a jurisdiction where the science counts for something. Where there was a lot of anxiety and apprehension about the last event ... I think there's a lot more confidence going into this one and it's going to be epic."

Mr Barr, who announced his decision on Monday evening via Facebook after the government did not respond to questions from The Canberra Times earlier in the day about whether a decision had been made, said the decision reflected the government's responsibility to not only try to prevent drug use but to support initiatives that reduced the harm associated with drugs.

"Pill testing does not make taking illicit drugs safe and our message to the community will always be, don’t take drugs," he said.

"However, pill testing provides a health intervention at the point when someone is making the decision to take a pill."

Last year's trial saw 125 people visit the pill-testing tent during the Groovin the Moo festival. Of the 85 drug samples provided, 83 of them produced usable test results.

Data from the trial showed that more than 80 per cent of participants believed they were taking MDMA, also known as ecstasy, when in reality less than half of the samples collected contained the substance in a relatively pure form.

It found that patrons as young as 15 years old had brought pills to the festival, and 45 per cent of those taking part were 20 years old or younger. Only five festival-goers were seen to discard their drugs, but a final report later said "numerous discards" were found in the vicinity of the tent after the festival.

None of the people who had their pills tested in last year's trial ended up in hospital or presented for treatment.

The trial also provided information about the types of illicit substances that are in the ACT, as well as two potentially deadly substances that were identified in two tested pills, Mr Barr said.

One of the substances was responsible for the hospitalisation of 13 people in New Zealand a month earlier.

"Given the increasing interest in pill testing, we consider this trial to be of enormous value to the debate and deliberations about harm minimisation," he said.

"To build on the information we have, the ACT government is ensuring there will be an independent evaluation as part of the trial, which we will make available to other jurisdictions."

The trial will be run by Pill Testing Australia (rebranded from STA-SAFE) at this year's sold-out Groovin the Moo festival, which will be held on April 28 at Exhibition Park.

Last year's festival was held at the University of Canberra, but the university decided not to host the festival this year, saying the campus was no longer "fit for purpose" to hold an event of that size.

Late last year, the National Capital Authority refused to allow pill testing at the Spilt Milk festival at Commonwealth Park, which is land controlled by the federal government.

"The government does not support decisions to use illicit drugs, and does not in-principle support pill testing, as it could imply that illicit drugs are safe," it said.

"Importantly, there is no legal framework currently in place and the Commonwealth will not facilitate measures to enable pill testing to take place on Commonwealth land."

With Andrew Brown