Tenants Protection Association (Auckland) co-ordinator Angela Maynard said many Aucklanders were already shut out of the housing market because rents were too high.
"They need to consider whether or not people can afford to pay these rents."
Those on low incomes would fare worst, as welfare and wage growth would not cover rent increases, forcing some tenants into homelessness, she said.
Auckland Property Investors Association president Andrew Bruce urged landlords to set rents at market rates.
"You'd be crazy to say, 'the market is bubbling away, let's see if we get over-market'. In the end that works out worse for everyone because you end up having more vacancies, and vacancies are the thing that kill you as a landlord."
Just because rates were going up 9.9 per cent, it did not automatically follow that landlords would immediately put prices up, he said.
"But in saying that, if you start making things harder for landlords, and their costs are going up, it will have an impact," he said.
Federation of Family Budgeting Services chief executive Raewyn Fox said many families were already paying more than half their income on housing costs.
She questioned whether rents reflected the actual cost to landlords of providing accommodation in Auckland, or if some were just "taking advantage of the market".
Kitchen-less flat 'ridiculous' at $285pw
An Auckland couple living in a studio apartment with no kitchen say they are paying $285 a week after their landlord raised the rent by $10.
"I think it's ridiculously expensive for what it is," the woman told the Herald.
The Sandringham building's rooms were run down, with leaking taps, mouldy shower steps, squeaky floorboards, rotting bathroom cabinets and a continuously dripping shower unit "falling off the wall".
"Also, there are six ovens in the shared kitchen and only half of them work."
She said the building manager and owner had known about the problems for six months but done nothing to fix them. "I would love to move out of Auckland, but my husband and I are stuck here because of our jobs.
"We are in our early 40s and don't think we will ever be able to move out of this place, which means we will never be able to have children ... [and] definitely never own a house."
Meanwhile, Otahuhu woman Rachel, 54, has lived in her one-bedroom flat for 25 years. She pays $215 a week. "That's really cheap."
After paying for bills and food she has little left over in terms of disposable income. "I just make do ... tightening the belt. It gets to the stage where you just can't tighten it any more."
What Auckland landlords say
43%
will raise rental prices to cover part of the increased rates
33% will raise rental prices to fully cover the increased rates
24%will not raise rental prices to cover the increased rates
