Water Issues
The two real issues are salt intrusion and environmental impact. It is technically correct to say we will never run out of water. What we will run out of is the drinkable (and cheap!) Aquifer water.
First the environment, for every drop we pump there is a loss at the end of some stream or marsh somewhere out there. How much we "should" take and how much wetland impact we are willing to tolerate is a moral issue.
Next, and more importantly, is salt intrusion. If you pump more clean water than soaks down through to replace it you will decrease the clean water bubble. What seeps in to replace it is the high salt content and / or polluted surrounding ground water. Eventually right up to your pump's "straw". Bad move - well is ruined.
Water Facts
The St Johns Water Management District is the state agency of experts that dictates how much water we can pump. It is measured in Millions of Gallons per Day (MGD). Your allocation is granted in the form of a Consumptive Use Permit (CUP). They are periodically reviewed and renewed but rarely to never increased. We on average pump 12.5 MGD. During special events or other high use days we hit 14.5 MGD. Our CUP limit for 2007 is 15.35 MGD. It increases little by little through 2011 when it caps at 16.16 MGD. It's all we can hope to get. Once we use up the rest of our allocation we will spend hundreds of millions on alternative water treatment facilities. Tax watchers will love this one... These gallons are also MUCH more expensive to produce and will be converted from sources such as: salt water, reuse city water & surface lakes.
See for yourself
Public records are a great thing if you know what to ask for. My water information came from A Consumptive Use Technical Staff Report, Application from November 9th, 1999. This document is the "turndown letter" Daytona Beach received when we asked the District to increase our CUP. We had an allocation of 16.02 MGD and we requested them to increase it to 20.5MGD by 2010. They granted us an increase of only 00.14 MGD and that does not come untill 2011. You can ask any credible source about the District's politics and environmental stance. 16.16 is all we will likely get.
The 2nd image below is a proportional scale comparison of our current growth, total density obligation, current water use, and total Aquifer water availability. Not a great picture.