At one point, not long after I received the crystals..I left my water crystal in a jar of water for an extended amount of time. I don't remember exactly how long now but it was in the same jar of water for several days. I didn't leave the crystal in the water with the intention of charging it and I kept it away from sunlight and moonlight while it was in the jar...I just realized after the fact that the crystal probably shouldn't have been sitting in the water that long. Would the crystal being in water that long deactivate the charge?
Personally, I trust the original charging and keep them out of the sun or especially the moon. Why try to improve on the orignal source of the crystal's charge? The water crystal is charged for more than one gallon of water I would think. I see no expiration date on it.