We drink about 110 million litres of bottled water a year - five times more than a decade ago.  But will recent reports of contaminated water supplies drive us to spend even more money on it and what exactly is the difference between natural mineral water, spring water and simply 'bottled water'?  Iva Peacock finds out

'Twenty years ago, if you tried to sell a bottle of water for £1, people would reckon you should be certified," says Alan Reilly of the Food and Safety Authority of Ireland, which has overall responsibility for the enforcement of bottled water legislation.

But over the last decade we have dramatically increased our consumption of the clear stuff. Why are people buying more and more water in bottles? While marketing is undoubtedly a key reason, concerns about water quality are also leading to increased sales.

The Environmental Protection Agency figures released recently which show that 25 per cent of group water schemes are contaminated with human or animal waste may result in increased sales of bottled water in rural areas.

John McLelland, senior buyer with Superquinn, reckons that concerns about tap water quality is one of the reasons that bottled water sales continue to grow by between 10 and 20 per cent every year. "Whenever there is a water scare in a town, we always see a major increase in bottled water sales and afterwards they don't necessarily go back down to the levels they were at," he says.

Kieran Hynes, managing director of the natural mineral water supplier Glenpatrick, based in Clonmel at the foot of Slievenamon, Co Tipperary, agrees: "I think there is a big issue with contamination of public water supplies."

The boom in bottled-water sales is not reflected in the increase in water filter sales, says Adrian Hamilton of Simply Water, which has been selling internationally-certified products capable of removing all bacteria, parasites, chlorine and fluoride since 1989. "Although people know their water is bad they aren't responding and making county councils buy filters. Instead, people are buying bottled water."

One filter user in Athlone said he and his wife didn't like the taste of the tap water and everyone was advising them to boil it. "A filter is way cheaper than buying bottled water and it seems to do everything that bottled water does," he said. The over-riding factor for him was: "we'd like to drink water from the tap". But it seems the trend towards becoming more European in our water-drinking habits is set to continue. In 2000, we drank over 50 per cent more bottled water than two years previously, although at an average per capita consumption of 22 litres a year, we are still only consuming a quarter of the quantity drunk by our continental neighbours.

It's a trend that Irish supermarkets have recognised over the past decade. Superquinn has had its own-brand bottled water for more than 10 years. Originally sourced from west Wicklow, its in-house brand is now supplied from Tipperary Natural Mineral Water's well. McLelland says its quality is thus assured and "we regularly do our quality assurance checks".

Tesco and Marks & Spencer have their own brands which are also supplied from Co Tipperary but from the 800 metre deep wells at Glenpatrick's facility. Glenpatrick managing director, Kieron Hynes is adamant that his company "offers more than just water". It is, he says, "a product that is verified to be safe and which, compared to other products, is relatively inexpensive".

And it seems that despite our lack of water charges, we are going to keep buying more and more bottled water. As Mary Flynn, Ballygowan's marketing manager, says: "It has now become part of modern lifestyles".

As our taste for packaged water has grown, so have the regulations regarding its production. Bottled water companies must comply with either one or two European Directives - depending on the type of water they are selling - by meeting an Irish bottled water standard, which was first introduced in 1992 and updated in 2000. "In the 1990s, the Irish bottled water industry lobbied us to produce national standards as a means of them complying with EU legislation," explains Manus O'Brolchain, who has responsibility for the development of food standards with the National Safety Authority of Ireland (NSAI).

"This covers protection of the well, drilling of all boreholes, the management systems in place for protecting the groundwater aquifer and the minimum level of testing," he explains. Companies which meet the standard are certified every year by NSAI assuring compliance with European legislation.

But bottled water is not simply water in a bottle. As with the variety in packaging sizes, shapes and types (glass, plastic and aluminium cans), there are also differences in the definitions of bottled water - it falls into one of three categories - natural mineral, spring or plain bottled water.

Alan Reilly of the FSAI describes water which is classified as "natural mineral water" under European regulations as "the grade A" of bottled water, with "spring water" holding the "grade B" position. However this grading is not reflected in the number of criteria with which "natural mineral" and "spring" water must comply.

Ironically "grade A" must only comply with the EU Natural Mineral Water directive while "spring water" must comply with both this directive and the more general Drinking Water directive.

Only companies which source their supply from waters recognised by the EU can market their product as "natural mineral waters". Ballygowan, Glenpatrick, Kerry Spring and Tipperary are the only recognised Irish "natural mineral waters" whereas there are over 60 such recognised sources in France.

Key criteria of the "natural mineral water" classification are that the water is from a bacteriologically-safe underground source and that it is not treated before bottling.

The EU Health and Consumer Protection website explains: "though legislation in force on natural mineral waters guarantees a high level of purity and ensures that the water is free from all environmental contamination or pollution it does not provide for any maximum limits for undesirable constituents of natural origin. In contrast, the Directive on drinking water does make such provisions for drinking water and spring water."

So "spring water" can undergo some treatment in order to ensure that minerals it contains fall within the maximum limits set under the Drinking Water Directive. Bottled water by comparison, which is neither classified as "natural mineral" or "spring water", is considered the lowest quality bottled water, as it can legally be chlorinated and treated in the same manner as municipal water supplies.