Health experts have been relying on the Australian Health Survey (AHS) to say the average Australian consumes 6.2 grams of salt a day, which is marginally higher than the World Health Organisation's recommended maximum of 5 grams and therefore little cause for alarm.

But the true figure could be as high as 9.9 grams of salt per day.

Researchers at George Institute for Global Health analysed the salt intake of 419 residents of Lithgow using two methodologies - a 24-hour diet recall questionnaire and 24-hour urine samples.

Based on the diet recall method, which was used by AHS, the average Lithgow resident consumed 6.4 grams a day - similar to the AHS result.

But based on 24-hour urine collections, the researchers were able to conclude the average was actually 9.9 grams per day, once salt lost through sweat was taken into account.

This is the first effort to estimate salt consumption based on urine samples, a superior research method.

"At a mean intake of 6.2g/day salt would not be a priority for public health because this level of consumption is only marginally above the target set by WHO, and far better than almost every other developed country," the authors wrote.

"At 9.9g/day, however, the picture is entirely different [because it] is double the WHO's target for daily salt intake and suggests a several folds greater disease burden attributable to excess salt consumption in Australia."

High salt intake is a major factor contributing to cardiovascular disease and a small reduction can lead to big health benefits.

Co-author Associate Professor Jacqui Webster said people were failing to realise just how much salt they were adding to their food either while cooking or at the table.

"Then they are being hit with the hidden salt in some of our most commonly consumed foods - breads, processed meats, soups and sauces and salty snacks," she said.

She urged manufacturers to reduce the amount of salt in their formulations.

"We've had some progress through government salt reduction targets but efforts need to be increased," she said.

"Our results show a pressing need for a co-ordinated approach by government, industry and the public to reduce salt consumption."

An Australian Food and Grocery Council spokesman said the industry was working with retailers and stakeholders such as the Heart Foundation and the federal government to reduce the levels of salt in food.

"Industry has already made significant reduction in sodium levels across most major food categories [and] the Australian government's Healthy Food Partnership is continuing the push with manufacturers and retailers to reduce sodium across their product ranges," he said.

"We encourage people to be conscious of their salt level intake according to dietary guidelines, by using the sodium information that is clearly provided in the nutrient information panel, in the Daily Intake Guide and incorporated in the Health Star Rating labelling system."

Dr Seema Mihrshahi from Sydney University's School of Public Health said the researchers' conclusions were "valid and important".

"It's a great study and the first ever to estimate salt consumption based on urine samples, but it needs to be repeated in other contexts," she said.

The study found the food categories that contributed the most to salt consumption in Lithgow were bread and cereal products, meat dishes, soups and savoury sauces and condiments.

The research, published in Public Health Nutrition, was released on Wednesday to mark World Hypertension Day.

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