Have you ever wondered how Ibiza, a tiny island with no rivers or streams, and in the middle of a salty sea, gets its fresh water? The answer is of course by way of a vast underground geometrical 'pipeline' of porous rock sandwiched between harder non-porous layers which connects the island to the mainland and is known as an aquifer. So when the rain in Spain falls mainly on the plain, it is channeled via the aquifer to Ibiza where wells are bored to extract the fresh water. However, with the demands of millions of tourists every year the level of water in the aquifers has fallen due to overexploitation and the water has become contaminated by salt. Recent tests have demonstrated the in the main areas of population the level of salt in the water has increased by over 1300% since 1983, making tap water unpleasant, but not particularly dangerous to drink.