More than 600 visitors to Banstead Countryside Day took part in a taste test to see if they can recognise their local tap water.
Most of the participants, both young and old, were unable to tell the difference between the three samples at the event in Banstead Woods.
The majority also preferred tap to bottled water, Sutton and East Surrey Water said.
Anthony Ferrar, managing director of Sutton and East Surrey Water, said: “Our tastings continue to show that most people cannot tell the difference between their local tap water and bottled water - and it’s just as good for you. Of course, the real difference is that bottled water is 1,000 times more expensive.”
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