'Footprint' for water

Consumers will be able to gauge the water "footprint" of products under a labelling move experts believe will benefit New Zealand.

Following on from carbon footprints and food miles, moves are under way to include water information on labels.

The information would measure the volume of water used in the life cycle of a product or service.

United Nations' cultural agency Unesco says it takes a global average of 200 litres of water to produce a 200 millilitre glass of milk, while a glass of wine takes 120 litres and a hamburger 2400 litres.

A Unesco report says it takes five times the amount of water to produce an Australian kiwifruit as it does to produce a New Zealand kiwifruit.

A Royal Society of New Zealand discussion paper, released yesterday, said water sustainability issues were "unavoidable".

The International Organisation for Standardisation is developing a water-footprint protocol, which New Zealand companies like kiwifruit marketer Zespri and dairy giant Fonterra are already considering.

"If you did this the right way, it would be a big advantage," Royal Society analyst Dr Jez Weston said.

"Let's face it, New Zealand has got a lot of water.

"Compare us to a lot of overseas products and we are a lot less water-stressed."

Zespri innovation leader Alistair Mowat said retailers had not requested water-use information, but retailers and grocery chains in the United States and Europe were developing policies.

The next step in New Zealand was a case study of a domestic horticultural crop.

Water Rights Trust chairman Murray Rodgers said the environmental footprint of water use was more critical than water availability in New Zealand.

Allowing environmental degradation from farming was effectively a subsidy for dairy companies, he said.

"That's a significant risk for our export sector."

Water-footprint labelling on products is still some years away. The Royal Society paper said the water debate was behind carbon by five or 10 years.

Carbon-footprint labels have taken off in Britain, where more than 2500 products carry a measure of the carbon embedded in a product's life cycle.

A similar scheme starts in Australia next year.