Willam - The tap water may simply be degassing to come to equilibrium. Keep in mind, that the water is at a pressure of between 60 to 100 psig when it is in the pipes. Any disolved gasses will be in equilibrium at the elevated pressure (and likely reduced temperature). Once you run the tap water, the pressure drops to atmospheric pressure (some wheres in the neighborhood of 14.7 psia). Once the pressure is relieved, some of the disolved gasses will naturally want to come out of solution, to reach a new equilibrium at the reduced pressure. Another way to think of it, is to think of a normal bottle of soda. When the cap is on a new bottle of soda, it tends to be all liquid. However, once the cap is opened, the pressure is relieved and the soda begins to release the CO2 gas from solution. If the cap is left off long enough, the soda will go flat (no more gas bubbles).
I would suggest drawing a container of water and allowing it to rest over night. Once the water has come to room temperature, and had time to offgas, your bubble problem will likely go away (or at least be minimized).
PS - Let me know if you need help disposing of the gin.
