| MadSci Network: Chemistry |
Hi, Rob. Water is a universal solvent, meaning many things dissolve in it. Tap water owes its taste to dissolved gases and minerals. Leaving tap water out for several days is not distillation. Distillation is a process of converting water into steam and then changing the steam back into water again accomplished in a distiller. Water loses its ions in this process. As a result, distilled water also called 'pure water' doesn't have much taste or smell.
What does occur to standing water however, is evaporation. As water evaporates you may have higher concentrations of minerals like iron and manganese. The water also picks up gases and pollutants in the air which dissolve in it. You'd be surprised as to what is in the air. Skin flakes, textile bits, dust particles, insect fragments, carpet fibers, formaldehyde and fungal spores for starters. As the chlorine evaporates the odor of dissolved hydrogen sulfide, (the smell of rotten eggs), may become more pronounced. These substances may degrade the taste, odour or even the appearance of water. Cold water, fresh from the tap tastes 'fresher' as there is more dissolved oxygen in it. An aerator accomplishes the same thing.
So get yourself a tap aerator, let the water run for about a minute until it's cold, (and also to let out any impurities.) Now sit back and enjoy immediately.
"Here's lookin' at you".
Hope that helps. Peter Bosani.
Sources: The Secret House - David Bodanis
Consumer Reports - 1987 & 1990.
Try the links in the MadSci Library for more information on Chemistry.