A water table is a source of fresh water that is located underground. In terms, of the Ko'olau mountain range, it is an aquifer. Which is a permeable source, meaning it is easier to drill down to get the water. In the case of Honolulu, we use the Ko'olau Basalt aquifer to derive the freshwater for our use.
(http://emp.trincoll.edu/~lpolate/mic/water_shortage/improvement.htm)
The way that the water table works is as the water gets depleted via the wells, water is continuously replenished in the table. In the case of the Ko'olau Basalt, it relies completely on rain. The Ko'olau mountain range is continuously getting rained on throughout the year. The rain makes its way down into the Earth. It takes YEARS for the water to bypass layers of dyke rock in a natural made filtration system.
However, because we use up more water than is getting filtered down, the amount of available freshwater is decreasing dramatically. So save water guys!
