There's nothing wrong with keeping the body hydrated with the healthy optimum of eight glasses of water a day. But you may want to think carefully about your source

Stocking up on plastic bottles of spring water could swell your carbon footprint, while some claim that tap water may not be as pure as it looks. Could you bottle out of mineral water or pull the plug on tap water?

Message in a bottle

Bottled spring water may come straight from Mother Nature, but as with other imports, air miles are clocking up on the carbon emissions counter.

According to the Chartered Institute of Water, nearly a quarter of bottled water supplies cross national borders to meet customers and 22 million tonnes of bottled water are transferred from country to country. Italy, Europe's largest mineral water drinker, sells 280 brands of mineral water alone.

The Evening Standard reported this year that bringing water into the UK produces approximately 33,200 tonnes of CO2 emissions. That's the same as the yearly energy consumption of 6,000 homes.

Amy Dutton, Thames Water's spokesperson, is encouraging people to turn to tap. She says: 'We recommend people switch to tap water to reduce their carbon footprint as packaging and transportation increases carbon emissions. Bottled water is 300 times higher in CO2 emissions per litre than tap water, which releases just 0.0003 kg of C02.'

Are bottled brands all bad guys or are we going carafe-crazy? Not all spring water is flown into the UK. Many suppliers source their water from local springs and sell to customers within our shores, like Minton Pure Spring Water from Dartmoor.

Mehmet Seferoglou, Minton's general manager, says: 'We must have the lowest carbon footprint! Our water comes from Devon and we supply shops and businesses in the UK. We have a fantastic local customer base in Devon, so our water comes straight from the ground and then travels a couple of miles down the road. Perrier and San Pellegrino have a larger footprint than us!'

Highland Spring also claim that three quarters of their bottled water produced in the UK fills British glasses.

Exporters Danone, who produce big brands Evian and Volvic, claim their footprint is a tiptoe. They state that the CO2 from one litre of bottled water is one-thirtieth of that of one kilogram of organic chicken.

Plastic bottles

Can we be green and drink mineral water when plastic bottles are derived from one of the world's most scarce resources, oil? The Earth Policy Institute reported in 2006 that 1.5 million barrels of oil were used to make 26 billion bottles of water in the US. That's the equivalent of running 100,000 cars each year.

But could we make things better by recycling our empty plastics? Danone say that the UK has one of the lowest recycling rates in Europe. The Waste and Resources Action Programme reports that three out of four bottles are not recycled. Three million bottles per day arrive in landfill sites which, according to the Container Recycling Institute, take 450 years to break down.

Mehmet Seferoglou from Minton says bottled water customers are becoming more aware of recycling: 'A lot of our customers who traditionally preferred glass bottles are now switching to plastic as it is easier for them to recycle,' he explains.

There isn't just waste from plastic. The amount of wasted tap water that escapes down the plug is immeasurable, according to Thames Water.

Spokesperson Amy Dutton says: 'The average person uses 150 litres of tap water per day. Two litres of this is for drinking and the rest for washing and cooking. We encourage households to be more water efficient, to use water butts, save a flush, turn off taps when brushing teeth and to take showers rather than baths.'

What's in a glass?

Chemicals are added to tap water to make it drinkable and kill off bacteria. There are claims that traces of a chemical cocktail can be found in tap water. Mehmet Seferoglou says: 'There's chlorine, fluorine, arsenic, radium, aluminium, copper, lead, nitrates, pesticides and hormones in tap water.

'The water in the Thames has been through someone's body three times and then sits outside our homes in a lead pipe. If tap water is so good for you, why do people recommend that it is boiled before it's given to newborn babies?'

Amy Dutton, of Thames Water, sets the record straight when it comes to chemicals in tap water.

'Thames Water and the rest of the water industry use chlorine to disinfect water and stop the spread of infectious disease and we've been doing that for years. The levels are carefully controlled and monitored and are less than 1mg per litre, the recommended amount by the World Health Organisation.

'The only chemicals we use are chlorine, iron - an essential nutrient - and aluminium salts (used in two Thames Water areas) to clarify the water. The levels are one-tenth of the recommended level.'

Going underground

Old lead, underground pipes have been said to taint tap water en route to our homes. Mehmet Seferoglou claims: 'The water is sitting under our homes in a lead or clay pipe. In our factory, we extract our own water and use stainless steel pipes, which are cleaned and sterilised every day.'

But Amy Dutton says: 'I can confirm that there is essentially no lead present in the drinking water we supply as it leaves our treatment works. The network of mains which transports the water to your tap are not constructed from lead.'