Excerpts from the "Pool of Radiance" module, by Sean K Reynolds:
"Pools of radiance are essentially raw pools of magic represented as water. The inherent magical energies of the Weave of Faerun sometimes amass in a particular place, always taking the form of a pool, whether in the middle of a desert or in a secluded grove."
"A pool of radiance, for all practical purposes, is an exposed nerve of the magical body of Faerun."
"The pool itself can be used as a source from which those highly attuned to magic can bolster their abilities with incredible power."
"More often than not, mages attempting to use a pool to fuel their magic find themselves dealing with magical backlashes and strange side effects."
"Nevertheless, the pools are among the most potent sources of magical energy in all of Faerun. Tales among spellcasters speak about how some being came in contact with a 'magical pool of water' and was bestowed with extraordinary abilities and powers."
The module contains some details of what happens when a character comes into contact with the Myth Drannor pool, which had been corrupted. Thus, its effects are keyed towards undeath, evil, and dragonkind.
Hope this helps!