DDH1 Drilling managing director Murray Pollock said drug use was a major stumbling block in recruiting new blood to meet increasing demand from explorers and miners.
His comments were echoed by Wallis Drilling managing director Graeme Wallis, who said failed drug tests were an unfortunate reality in recruitment.
Other factors have also contributed to a shortage of experienced and entry level drillers, including the move last year to cut drilling from the 457 visa scheme for overseas workers.
Mr Pollock said public perception issues for the mining industry caused by mass retrenchments during the downturn and high labour demand for building projects in Australia's biggest cities had contributed to the labour shortage.
"What I'd say from my long experience is that it has never been more difficult to find drill rig employees in Australia," he said.
"That is not just in the last six months, it probably goes for the last 18 months. The further we go, the worse it is getting.
"A few years ago the mining industry was viewed as the place to be and people felt if they were not involved, they were missing out.
"Once mining industry activity fell away and there were mass retrenchments, especially from the big end of town, I think the mining industry quickly fell out of favour."
DDH1 employs more than 400 people and has offices in Western Australia and Queensland, where recruitment has been slightly easier. Gold dominates its book followed by copper, zinc, lithium and nickel.
ASX-listed Ausdrill recently warned that skill shortages were a threat to exploration programs and urged the federal government to reconsider the 457 visa exclusion.
Wallis Drilling, which leans toward the iron ore industry, retained most of its 250-plus workforce as people left the industry in droves during the downturn.
"It is hard to find good drillers and we are finding it very hard to get new ones in," Mr Wallis said.
Mr Wallis said mining companies had put the screws on drillers during the downturn, but prices were coming back.
"It is picking up and picking up quickly," he said. "We are knocking back work and others are knocking back work. Prices are going back up and people will need to accept that or not get a drill rig."
Mr Pollock said it was time to reinstate the 457 program for drillers, which in the past saw a high proportion of overseas workers employed underground.
"There has never been a greater reason to have 457 access for the drilling industry for skilled employees. We almost need it for all levels, but we are never going to get it for entry-level people," he said.
Mr Pollock and Mr Wallis both said they would employ and train more new workers if they were available. However, drug use was a significant issue among those who did apply.
"It [failed drug tests] has increased over the last two or three years and that is a real issue," Mr Pollock said.
"They are going for an entry-level job that with super is going to provide them with $90,000 to $95,000 a year and the opportunity to learn and increase their earning ability, but they are precluded from that by their drug use.
"They'll do all sorts of devious things to get into the door so it's not that they don't want to work, but they're drug users."
Mr Wallis said: "There are no two ways about it. People come in or inquire about a job, they do the drug test and quite a few we don't see again."