glass recycling issues and solutions

The Glass Story

Let’s make good into great

Glass as a packaging material has a great circular economy story to tell.

It can be endlessly recycled at the end of its life and in some instances be refilled to keep it in circulation longer before it’s recycled.

Both refilling (reusing) and recycling save resources, energy and carbon emissions. In New Zealand we have a high glass recovery rate, but there’s still plenty of room to improve how much is recovered, reused and recycled.

What’s holding us back from doing better?

Knowing just how much we are using, reusing, recovering and recycling

It’s important to know how much glass we are using, recovering, reusing and recycling so that we know how well or poorly we are doing.

Every year the GPF collates the best available data to understand how much glass is consumed, how much is recovered and what the outcomes are. But as with other packaging material, there are no official public records kept.

We rely on co-operation from manufacturers, importers, brand owners, councils, and waste management companies to fill in the gaps. They all have different ways of keeping records for different purposes.

The best sources of data are only available at the beginning and end of the glass lifecycle, with little available in between.

Solution – data collection is regulated

Government regulation, requiring all members of the supply chain to report glass data in a uniform, way would ensure reliable and consistent information at all steps along the glass lifecycle. This would be invaluable in making decisions which impact glass recovery for recycling or reuse.

Regulation could include a system to track all waste streams and outcomes, as many other materials have the same issues around measurement and data.

Read more about how we collate our data

Different recycling collection methods around New Zealand

While New Zealand has standardised what materials are collected at kerbside, not all councils collect glass in the same way. Many councils use the best practice method of collecting glass bottles and jars separately and colour sorting them, but a few others use a co-mingled (everything in one wheelie bin) method which requires additional sorting and results in higher loss of materials.

While the GPF has advocated for and has seen more councils move to glass separate collections, more than half of all New Zealanders are still serviced with a co-mingled collection.

Solution – collecting glass separately in kerbside collections

Collecting glass separately to other recyclables, will result in a consistent supply of high-quality colour-separated glass (cullet) for recycling.

Find out more about best practice collections


Contamination of the glass recycling stream can occur at multiple points. During collection there is the risk of people putting non-recyclable glass (light bulbs, window glass, cook ware etc) or other recyclables into glass collection bins.

Co-mingled collections where glass, plastic, paper and metal are collected in the same bin, result in recyclables contaminating one another. This requires more mechanical sorting and resulting in loss.

Contamination can also occur during storage when infrastructure is not fit for purpose. This can result in glass stored in its separate colours spilling over and causing cross-contamination. Detritus like soil and stones can also contaminates glass when it’s loaded for transport if storage bunkers aren’t correctly built.

Solution – better collection methods, education and promotion

A standardised, national kerbside collection method whereby glass is collected separately would greatly reduce the risk of other recyclables contaminating glass and vice versa. This would also make education around correct recycling practices simpler and more cost effective as the messaging would be universal.

A report from NZIER found the majority of the population is enthusiastic to recycle but lacks the necessary information to do so correctly. Effective and ongoing education and promotion is therefore needed.

Investment in storage infrastructure has been a major focus for the GPF and has shown to improve the quality of collected glass as well as make transport more efficient.

Find out what you can and can’t put into your glass recycling

Logistical challenges

Transporting glass bottles and jars to be recycled can be logistically challenging, especially when they must be moved long distances to the glass manufacturer in Auckland. Transporting glass to be refilled is also challenging, as it must be kept whole and undamaged.

Solution – hub and spoke model, increased storage capacity, better utilisation of backloading, coastal shipping

Bigger, bulk loads make transport more viable so the GPF has advocated for and supported the creation of hub-and-spoke models. These see glass from outlying areas in a region aggregated at a hub before being transported in bulk.

The GPF has also actively worked to increase storage capacity at recycling depots around the country, particularly those which operate as a hub, through grant funding allocations.

Who pays?

Household recycling and public recycling bins collections are paid for by councils and ratepayers. Commercial collections are paid for by businesses, and currently there is not much incentive for them to choose recycling over landfill.

The idea of product stewardship is that those who make, import, sell and consume a product (or packaging) are the ones who pay for its recovery and recycling, reuse or proper disposal at end of life.

Voluntary schemes like the GPF primarily suffer from free riders – industry members who don’t contribute financially to the scheme but whose products are included in the scheme nonetheless. This hinders a scheme’s ability to set fees at a level to cover the whole cost, because free riders have a competitive financial advantage by not participating.

Solution – regulated product stewardship

Regulated stewardship ensures all members of industry participate and contribute financially to cover the full cost of reducing the environmental impacts of their products (or in this case packaging). This levels the playing field, prevents free riders and bolsters funds available for improving outcomes for glass.

It also means systems can be co-designed by everyone involved for funding, collection, transport, reuse and recycling to help us achieve the best outcomes most cost-effectively.

The GPF has asked Government to enter into a co-design process for transitioning the GPF’s voluntary scheme to a regulated one.

Find out more