Thousands of tonnes of glass salvaged yearly from household rubbish bins could instead be sent to landfills if Auckland Council chooses a system of one bin for all recyclables throughout the region.

Glass maker O-I New Zealand told the council's waste plan hearing yesterday that a proposal for one collection of fully mingled wastepaper, cans and bottles from 240-litre wheelie bins would be a long-lasting setback to the council's drive to cut waste to landfill.

Company sustainability manager Penny Garland said that out of 78,000 tonnes of glass used a year in Auckland, about 42,000 tonnes was returned to be smelted in the furnaces of its Penrose factory.

"That's turning an old bottle into a new bottle."

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However, the co-mingled collections in some former council areas led to contamination, and only half of the glass recovered was recycled by O-I.

"In terms of sustainability, the fully co-mingled option is the worst option.

"Thousand of tonnes of glass recovered annually from the waste stream would be unnecessarily sent to low-level secondary markets, stockpiles, managed fills or landfills."

Ms Garland said the company believed the answer was to have a separate collection for glass.

In the Rodney area, a kerbside crate sorting system for all recyclables, with glass colour-sorted by workers, meant all recovered glass was recycled.

"We believe the split-stream proposal has wide support and will move the city to a little or no net cost situation and help reduce greenhouse gas emissions.

"We want to assure householders that when they put out a bottle or jar at the kerb, it will be recycled into a new container."

The council yesterday began the first of eight days of hearings during this month of views on its waste management and minimisation plan.

Councillor Richard Northey asked for evidence Aucklanders could "handle the sophistication" of having another bin just for glass.

Ms Garland said it was used in Dunedin and Wellington. "They are doing it and loving it."

Glass Packaging Forum chairman David Carter said 165,178 tonnes or 54 per cent of the glass recycled in New Zealand last year was used in making new glass containers.