Geopix Resources

Preview (from the Water Supply study guide):

Before entering our domestic water supply, water abstracted from the ground and from rivers undergoes various treatments to make sure that it is clean and healthy, and to remove some of the unwanted minerals. Clean, filtered groundwater requires (very) little treatment before being put into the supply. Adding chlorine kills microbes but can leave a nasty taste in the water (as you may have noticed when travelling abroad) so water which has not been chlorinated is more palatable, which has not gone unnoticed by firms selling (very expensive!) bottled spring water.

Mineral ions in groundwater

Depending on which they are, dissolved minerals can have beneficial or harmful effects. Fluoride ions. The classic example is fluoride, which is well known to improve the quality of teeth and to prevent their decay. The fluoride (in very small amounts) is dissolved from mineral veins containing fluorite (calcium fluoride). Some water boards monitor the amount of fluoride in their water, adding extra if necessary - although too much fluoride actually damages the teeth and causes other medical problems.

A typical bottled water contains 0.2 mg/litre of fluoride ions. Arsenic ions. Dissolved from metallic mineral veins, the metal arsenic is a poison which should not, ideally, be in drinking water. The former copper mining area of Alderley Edge, Cheshire (photograph right) would be barren of trees, poisoned by the arsenic, were it not for the re-planting carried out about a hundred years ago.