Environmental litter losses from ineffective maintenance of gross pollutant traps

Stormwater is a major pathway for anthropogenic litter to enter waterways and oceans. Gross pollutant traps (GPTs) are installed to intercept litter and other pollutants. However, their effectiveness relies on regular maintenance, including the removal of accumulated waste. In Australia, a national survey of municipal staff reported an estimated proportion of GPTs performing optimally ranged from 0%–10% to 91%–100%, with an average of 51%–60%. Municipalities that followed manufacturers’ maintenance guidelines or implemented formal servicing schedules were more likely to achieve higher functionality. Analysis of audit data from 33 municipalities revealed that 80% of GPTs were underperforming, with only 5% classified as fully operational. If all stormwater outlets had optimally functioning GPTs, we estimate 106,000 tonnes of litter per year could be prevented from polluting Australia’s marine environments. These findings highlight a broader global issue, suggesting that improving GPT maintenance could significantly reduce marine litter worldwide.