Police fear bars will be "swamped" when the country finally drops to level 2.
On Monday, Prime Minister Jacinda Ardern will reveal when New Zealand will drop a level in its Covid-19 warning system – with the move potentially coming as soon as 11.59pm on Wednesday.
Under level 2, bars and other public venues will be able to reopen if they meet key conditions.
As the nation waits on the announcement, the head of Auckland Police's alcohol and harm prevention unit, Senior Sergeant Morgan de la Rue, has spoken of potential pitfalls of the reopening.
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"People are sick up of being cooped up, so bars will be swamped but all we can do is hope for the best and plan for the worse," de la Rue told the Herald on Sunday.
He said bar reopening, combined with a rise in private gatherings, would make it a lot harder to manage social distancing and contact tracing.
"You saw how people reacted when takeaways became available," he said.
"So if you add alcohol into the mix with people going out drinking after being in lockdown for so long there is a potential for things to turn quite bad."
And he urged people to heed advice and rules, saying a worst case scenario featuring a spike in numbers of Covid-19 cases in New Zealand could see the country reverting to level 3 or even level 4.
"That would be a disaster," he said.
"Police are really going to have to enforce the rules. We are going to come out looking like the bad guys but all we are trying to do is protect people and avoid going backward."
De la Rue last week met via Zoom with 20 hospitality venue owners. The meeting was arranged by Leo Molloy, the owner of high-profile Auckland venue HeadQuarters.
Also present was Hospitality New Zealand and the bar and marketing manager from Viaduct Harbour Holdings.
Earlier in the week, Adern announced new rules for the hospitality industry under level 2.
Ardern recommended an approach dubbed the three Ss; which would see customers being seated, separated safely from others, and table service only.
Customers won't be allowed near a counter to pay. Payment should be taken at the table. A single staff member will also be charged with looking after separate groups.
De la Rue told the group: "Have a hard look at those guidelines and find ways that you can work within them to fit with your own business. If you think it's really difficult you should make a tough decision about whether you re-open.
"It's not about looking for loopholes or pushing the envelope. You have to think about what we are trying to achieve which is to stop the spread of Covid-19."
Bar owners asked de la Rue for clarity on the three Ss and also advice on a communal app to register guests and how they will work with the police about contact tracing and managing queues.
Molloy shared with the group he would keep tabs on his clients by registering them as "Friends of HeadQuarters".
They will be photographed and will be required to produce some form of ID with their name, address and phone number.
De la Rue said the Government is working on an app but it was crucial for business operators to collect as much information from their clients.
Jamie Freeman, operations manager of Joylab, wanted to know how owners would work with the police who have the power to shut down businesses.
De la Rue said, "We will work with you as best we can, there will be senior police on the street. We have discretion and can issue warnings but if it's still not working we may be forced to shut it down.
"We don't want to be heavy-handed, we just want businesses to get up and running."
He also said business operators would be responsible for managing their own queues.
Ideally, areas should be cordoned off to maintain the 1m self-distancing rule. But the police are still responsible for managing public areas
He told the group extra police will be deployed to patrol bars in the Viaduct, Britomart, Ponsonby and K Rd every night for at least the first two weeks.
If there were problems it was best to call 111.
"My personal concerns are not the licensed premises in the city but parties and gathering in the suburbs where there aren't the same restrictions," said de la Rue.
• Covid19.govt.nz: The Government's official Covid-19 advisory website