Every dollar spent on alcohol and drug treatment could save taxpayers at least $5, say experts.
They warn of a "pandemic waiting to happen" if the country's addiction problems are not addressed.
A paper released by the National Committee for Addiction Treatment (NCAT) yesterday revealed what one member called "horrifying" statistics, detailing devastation wrought by alcohol and drug addicts.
It also cited a 2005 United Kingdom study, which found that money spent on standard treatment therapies for alcohol problems saved about five times that amount in expenditure on health, social and criminal justice services.
National Addiction Centre director Doug Sellman said the difference was even more marked for drug addicts, where $8 could be saved for every dollar spent.
The statistics included:
89 per cent of serious offences are committed under the influence of alcohol and drugs.
Between 75 per cent and 90 per cent of weekend crime is alcohol-related.
Up to 50 per cent of men who physically abuse their partners have substance-abuse problems.
Alcohol plays a role in 30 per cent of fatal car crashes.
70 per cent of Emergency Department admissions are caused by alcohol abuse.
This happened in an environment where only 22,000 of New Zealanders with addictions accessed treatment services in any given year, leaving an estimated 138,000 unaided, NCAT co-chair Christine Kalin said.
Treatment costs ranged from $80 for an intervention for a low-level problem to more than $8000 for months of residential treatment.
Kalin, who released the paper at the Cutting Edge Addiction Treatment Conference in Christchurch, said staff in the sector were sick of turning away people who needed help.
"Anecdotally, I know that there are services that have waiting lists. Rather than building prisons, having health budgets overspent, having police resources stretched, let's put some of that money into services at the front end rather than the ambulance at the bottom of the cliff.
"At a very minimum, we need to have the capacity to treat the 160,000 who we know need special help, and help now," she said.
Alcohol Healthwatch director Rebecca Williams said the problem was probably worse than it appeared because people who could not access services were likely to be incorrectly recorded.
"This is a sort of pandemic waiting to happen ... I think services, if they were actually presented with all of the cases that needed help and support, they would simply not be able to cope."
Experts warned that turning people away often meant the window of opportunity to help them was missed.
Kalin said investment in the sector could take the form of community-based treatment options, aimed at specific high-risk groups such as schools and prisons.
Only one third of alcohol or drug addicts were thought to receive treatment while incarcerated, she said.
Associate Minister of Health Damien O'Connor, who addressed the conference yesterday, said the Government had increased its spending from $65 million in 2001 to $94m last year.
National health spokesman Tony Ryall said the party also recognised it was an issue, particularly for families of drug-affected young people, and would address it in its health policy.