An associate research professor at the Barcelona-based Institute for Global Health, she has spent years researching water. Ms Villanueva thinks that there is likely one significant factor behind the continuing boom in bottled water sales.

“The publicity and marketing of the bottled water industry, and [by contrast], a lack of publicity for public water supplies, probably has a main role, at least in countries like Spain,” she says.

She adds that while health authorities have a duty to ensure that mains water is safe, they would do well to be more transparent. More information about water quality would help ease people’s concern, she says.

Regarding bottled water specifically, Ms Villanueva says with much coming from natural springs, she is concerned that these sources “are prone to overexploitation” – that too much water is being extracted.

Simon Oldham says that is definitely not the case at Highland Spring, which comes from the Ochil Hills in Perthshire. “We extract no more than 3% of the rain that falls on our catchment, ensuring the long-term sustainability of one of the planet’s more valuable resources for generations to come,” he says.

“We are also very fortunate that Scotland’s climate has high levels of rainfall throughout the year.”

For anyone concerned about the quality of their tap water, an alternative to buying bottled water is to use a home water purification system, such as one fitted under your sink, or the filters that slot into dedicated water jugs.

This is also a booming global sector, with one recent report predicting that it will more than double from $22.6bn last year to $50.7bn in 2029., external

In Israel more than three quarters of the country’s drinking water now comes from desalinated plants on the Mediterranean coast. Other countries such as Saudi Arabia and the United Arab Emirates are also heavily reliant upon desalinated water, which tastes very flat and lifeless.

To improve the flavour of this water, and to help remove the chlorine, Israel firm Mayu makes a water jug system called “Swirl”. This comprises a 1.5 litre glass carafe that sits on top of a porcelain base unit.

The latter is battery-powered, and when turned on it creates an oxygenating spiral motion in the water in the carafe, which is said to improve its taste.