Is there plastic in our water supply?

Contamination has been found worldwide, but Auckland tap water is not currently tested for microplastics.

Watercare said its water was filtered and safe to drink but it was ‘‘proactively investigating’’ how to test for the small particles and fibres.

Current methods varied internationally and were not ‘‘completely reliable’’, water supply manager Priyan Perera said.

International research, reported by theguardian.com, has found 83 percent of the world’s tap water had microplastic contamination, including 94 per cent of samples taken in the United States.

Normally, between 8 and 15 per cent of Auckland’s tap water was taken from the Waikato River, downstream from the city of Hamilton and wastewater treatment plants.

Perera said Watercare filtered it, including with membrane ultra filtration technology.

‘‘Based on current understanding, membrane ultrafiltration is the most effective routinely employed treatment barrier to microplastics. This will be confirmed once a testing protocol has been confirmed and implemented.’’

Dr Trisia Farrelly co-founded the New Zealand Product Stewardship Council, and specialised in research on plastic waste.

She said it was reassuring Watercare was investigating microplastics in drinking water and that it was working out how to test for them. ‘‘It is essential that our municipal authorities are proactive in this regard as microfibres are the worst microplastic offenders when it comes to environmental and human health.’’

Farrelly said international reports suggested microfibres could be too small to be removed by sewage treatment plants. Those fibres were now present in most fish tested in New Zealand, she said.

‘‘Plastic microfibres leach endocrine-disrupting chemicals and carry persistent organic pollutants in increasing concentrations up through our food chain.’’

Farrelly said people should lobby the government and manufacturers of dryers and washing machines to do something about microfibres being released into waterways. They could also not wash synthetic clothing as much, wear garments less likely to shed fibres, and put washing machine lint in the rubbish, not down the sink.