Copper waste is contaminating waterways at a fifth of the water sampling sites around Christchurch.

It comes mainly from metal brake pads: every time a vehicle brakes, some metal is shaved off, and rain eventually washes it into rivers and streams.

A Christchurch City Council waterways ecologist, Belinda Margetts, said such heavy metal pollution is common to urban waterways, and can be fatal to wildlife.

She is calling on motorists to switch to copper-free brake pads.

“You can go and request copper-free brake pads but you might get a weird look from people who don’t really know how to supply that product,” she said.