Save your money and skip the bottled water. Chemical, biological and taste tests done by three sixth-year students from St Mary's College, Rathmines, has shown tap water wins out over bottled brands and filtered water.Through a glass clearly
"Our hypothesis was that tap is equal to or superior to filtered or bottled water," said Daniel Wu (17). He, Daniel Hardiman and Darragh Bracken Clarke have their findings on display at the Esat BT Young Scientist and Technology Exhibition under way at the RDS in Dublin.
The event reaches a climax this evening with the announcement of the four top group or individual prizes, to be presented by the President, Mrs McAleese. The exhibition is now open to the public and closes tomorrow evening.
The three students measured 12 parameters in 25 samples of tap, bottled and filtered water including chemical tests, acidity, taste and odour. They used 15 classmates as assessors for the subjective tests and either did their own chemical tests or brought in expertise from outside for aspects such as nitrate content.
Their findings will disappoint those intent on spending too much for this essential commodity. "Tap water was safe under all categories," Daniel Wu said.
The majority of tasters preferred it, although a tap sample from Navan tasted of chlorine and scored badly.They also found that popular water filter systems could leave drinking water so acid as to be outside safety limits set by the Environmental Protection Agency.
Most striking was the cost differential. One cent bought 7.14 litres of tap water, 0.26 litre of filtered water and 0.0 litre of bottled. The cost of a single half litre bottle of one popular brand was more than the cost of a full year's drinking water from a tap.
Mark Sims (16), of Lisdoonvarna secondary school in Co Clare, assessed preferences of a different kind. The fifth-year student carried out a comprehensive analysis of 2004 local election voting patterns in Co Clare.
Mark is a veteran at the Young Scientist, this being his fifth entry. Previous projects involved biological studies, but this undertaking involved only "inside" work - crunching numbers and pouring through electoral registers.
His original plan was to analyse newly published census data for the county but as his project evolved it focused on how the Clare electorate voted last summer. He combined details from the census, from tallies and the electoral register, refining the figures and applying them to each of Clare's 150 district electoral divisions (DEDs).
The results showed how each party fared in terms of first preferences. It also clearly illustrated what is known as the "friends and neighbours effect" in voting patterns and the tendency of voters to favour council candidates living near them.
Mark's electoral maps showed how first preferences were strongly local, usually overriding any socio-economic factors at a DED level.