Waiheke Island LittaTrap™ Trial Captures More Than 25,000 Pieces of Litter in One Year

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Plastic pollution entering waterways through stormwater networks is one of the greatest environmental challenges facing urban communities. Every rainfall event has the potential to carry litter from streets and public spaces directly into streams, harbours, and the ocean, where larger plastic items break down into harmful microplastics.

To better understand the scale of this issue and identify practical solutions, the Waiheke Local Board, in partnership with Downer and EnviroPod™, undertook one of New Zealand's most comprehensive stormwater litter monitoring programmes.

Over a 12-month period, 34 LittaTrap™ catch basin inserts were installed across Waiheke Island to measure litter loading, identify pollution hotspots, and evaluate the effectiveness of at-source litter capture.

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The Challenge

An estimated 80% of marine litter originates from land-based sources, with stormwater networks acting as a major transport pathway from streets to streams, rivers, and ultimately the ocean. Once in the environment, larger plastic items fragment into microplastics thatpersist for decades and are readily consumed by aquatic life.

At the commencement of the project, there was limited New Zealand data quantifying the amount of litter entering stormwater systems, creating knowledge gaps for councils seeking to reduce pollution at the source. The Waiheke trial was designed to provide real-world evidence of litter capture rates, identify pollution hotspots, and better understand seasonal and behavioural influences on litter entering the stormwater network.

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The Solution

Thirty-four EnviroPod™ LittaTrap™ units were installed in strategically selected stormwater catch basins across Waiheke Island.

The LittaTrap™ captures litter, plastics, organic debris, and sediment before they enter the stormwater network, preventing pollutants from reaching downstream waterways where they can degrade into microplastics.

Throughout the year-long study

• 10 x maintenance collections were completed
• 326 basket samples were analysed
• Every litter item was manually sorted using United Nations Environment Programme classifications
• Quarterly reports were produced to monitor seasonal trends and litter characteristics

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Project Results:

The trial produced one of New Zealand's largest datasets on stormwater litter pollution.

Key Outcomes:

• 34 x LittaTrap™ units installed
• 25,162 pieces of litter captured
• 18,097 plastic items intercepted
• 8,103 cigarette butts captured
• 326 basket samples analysed
• 15 site visits completed
• More than 500 hours spent sorting and categorising litter
• Average annual capture of 834 litter items per catch basin

Plastic was by far the most common pollutant captured, representing over 32% of all litter collected during the trial. Cigarette butts, food wrappers, soft plastics, hard plastics, polystyrene, and other plastic items were consistently intercepted before entering receiving waters.

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Key Findings:

Nine of the thirty-four monitored catch basins accounted for more than half of all litter captured, demonstratingthe importance of identifying pollution hotspots when implementing stormwater management programmes.

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Why LittaTrap™

The EnviroPod™ LittaTrap™ provides an effective source-control solution by capturing litter before it reaches waterways.

Key Benefits:

• At-source litter capture
• Helps prevent plastics breaking down into microplastics
• Laboratory tested to capture 99% of litter larger than 5 mm
• Simple hand or vacuum truck maintenance
• Typical maintenance only 1–2 times per year (Depending on site conditions)
• Quick retrofit installation into existing catch basins
• Supports long-term water quality improvement

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Conclusion

The Waiheke Island LittaTrap™ Trial demonstrated the effectiveness of at-source litter capture in reducing the amount of plastic and gross pollutants entering New Zealand's waterways.

By intercepting more than 25,000 pieces of litter over a single year, the project provided valuable scientific data while demonstrating how practical stormwater technologies can help councils protect receiving environments and reduce the formation of microplastics.

The study reinforces the importance of combining education, research, and proven stormwater treatment technologies to create healthier waterways and more sustainable communities.