Electricity and water don't go together. Just as how swimmers know to get out of the pool during a lightning storm, it seems intuitive that outlets should not be placed close to the kitchen sink. Nowadays, the distance from the sink to the outlet is actually less important than whether or not it has a ground-fault circuit interrupter (GFCI).
As of 1993, electric companies started requiring that all outlets have ground-fault circuit interrupters, or GFCI. The GFCI ensures that no one gets an electrical shock when they come near an outlet or touch something that is connected to the outlet. This serves as a preventative device to keep users safe when they plug something in. One major benefit of the GFCI is that it is no longer necessary to keep outlets far away from the kitchen sink.
How It Works
In order to send electricity through the line, an electrical source needs to be able to make a circuit. The electricity is sent from the beginning of the circuit until the end, providing the power source for whatever device needed electricity. If the circuit is left open, then anyone standing on the ground who touches the circuit or tries to plug something into the outlet will become the end of the circuit himself. Together with the ground and the outlet, he forms a circuit with his body and will feel a slight shock. A GFCI senses when a circuit is left open and interrupts the electrical surge, stopping it from reaching the person who has now completed the circuit. This prevents the person from being shocked.
Any house built after 1996 or that has had rewiring done since then should have full GFCI on all outlets. This ensures that you will not get shocked if you plug something into a loose circuit. Because of this new law, it is no longer a problem to place an outlet near a kitchen sink. Any surge or danger posed by the water will be sensed by the GFCI and interrupted before reaching the outlet's user.
Before GFCIs were common, it was required to keep all outlets at least 6 feet away from the sink. If your house was built or wired before 1996, it is a good idea to check if it has GFCI and to have these circuits installed if it doesn't. This should explain why all of your outlets are at least 6 feet from the sink and why you should not install any outlets closer than that. If your house was built after 1996, you can place the outlet considerably closer to the sink. In fact, there is no longer any official requirement for distance.