First there was tap water; then bottled spring water; now there is 'table water'. What is table water? It is tap water that has been purified in a filtration system.

Water filters are nothing new. But, according to the makers of the Fraser Milne Water Purification system (marketed by Classic Crystal, telephone 0844 274346), ordinary filters take out the chlorine, and small quantities, only, of contaminants. 'Once treated by our process,' says Tim Jones, the inventor of the system, 'tap water has a taste, freshness and drinkability unsurpassed by any other. It is the world's finest fresh water.'

The system costs a lot to install: up to pounds 800 for a private home, pounds 1,500 for hotels and restaurants. But what comes out is water that is up to 90 per cent cheaper than, and just as pure as, bottled mineral water.

The Fraser Milne system works on a seven-stage purification process using naturally porous ceramic earths, coconut and anthracite carbons, ultraviolet light and ion exchange to filter tap water. An initial pre- filter traps any debris; the ultraviolet light then destroys any micro-organisms that remain, and a ceramic membrane removes both them and any asbestos. Such pollutants (natural or man-made) as have survived all this, will be extracted as the water passes through four further filters.

In laboratory tests of 'spiked' water, undertaken for the company, the purification system removed an impressive 99.99 per cent of bacteria and 99 per cent of commonly occurring agricultural pollutants, such as the pesticides Atrazine and Simazine.

The laboratory results showed a similarly good performance for removal of industrial chemical pollutants, such as Phenol and 2,4,5 TCP, and an 89 per cent rate for aluminium. (Bottled mineral water should be entirely free of all these pollutants.)

The water tastes all right, too. 'We leave in enough of the minerals (sodium, potassium and so on) at desirable levels to make the water palatable,' says Mr Jones. 'Distilled water or totally de-mineralised water tastes horrible.'

Although bottled mineral and spring waters are estimated to cost 1,000 times more than tap water, sales in the UK have grown from almost nothing 10 years ago, to pounds 350m- worth a year. As consumer concern over tap water grows, purification systems look like being the next growth area.

Cadbury Schweppes is investing pounds 40m to construct 10 processing plants throughout Europe to purify mains water. The British plant is to be sited in the West Midlands, where it can draw on purer-than-average mains water from Wales. Even adding on the cost of filtration, bottling and so on, it will still undercut bottled mineral and spring waters. In the United States, carbonated, purified tap water is already on sale in bottles.

Mineral waters still claim to be the most squeaky clean, since European Union regulations require that they come from a 'naturally protected source of constant composition' and must therefore be 'free from all traces of pollution' without any disinfection, cleansing or purification.

True, bottled mineral waters have taken a few knocks. The contaminant, Benzene, was found in Perrier water in 1990; and, two years later, an Equinox programme on Channel 4 suggested that some mineral waters were over-mineralised (too high in such elements as sodium and potassium),

and insufficiently regulated compared with tap water.

These incidents have not put off H J Heinz and Marks & Spencer. This month they launch 'Pure Spring Water for Babies', which comes in a sterilised bottle complete with teat and will retail at about 49p a bottle. The water is being bottled by Gleneagles Spring Waters in Perthshire. According to spokesman Keith Wootton, the Gleneagles water has 'a very low level of nitrate and sodium and is bottled in sterile circumstances to pharmaceutical standards'.

The European Commission is taking legal action against the UK for failing to meet EU standards on pesticides in drinking water, which were unanimously adopted in 1980 with a five-year deadline for achieving compliance. Despite the fact that many water companies are still not supplying water which is up to standard, many derogations have been granted and no company has yet been prosecuted. John Gummer, Secretary of State for the Environment, wants to

allow water companies even longer to clean up supplies. He argues that their consumers cannot afford to pay the estimated pounds 1bn clean-up bill.

The Government is 'allowing legitimate public concern about rocketing water bills to let the polluters off the hook, despite its endorsement of the 'polluter-pays' principle,' says water campaigner Lianna Stupples of Friends of the Earth.

In the meantime, more and more consumers are faced with a range of personal choices about what water to use.

'Instead of paying out for expensive bottled waters, purification systems and the like, people should put their money and effort into campaigning for good quality, unpolluted tap water for everyone,' says Ms Stupples. 'Clean water is a right to which all European consumers are entitled, not something you should have to buy at additional expense. European consumers have a legal right to clean drinking water, and this is a right which is currently being denied.'

Our congratulations to Joanna Blythman, who this week received a Glenfiddich award for her food writing in the regional category.