After the moon is fully visible in the sky, take the jar outside and position it so the moon is reflected within. Maintain this position, looking at the moon's reflection in the water.
The water is now charged with lunar energy. Put the lid on the jar and save it. If you wish to add a verbal blessing, like below, you may do so, while contemplating the reflection of the moon.
Hail Aradia, fair lunar spirit,Lunar water can add lunar energies to any spell or blessing that involves water.
Bless this water with your power;
We are pulled by the moon, as are the tides.
This water should be saved only for one lunation, from full moon to full moon. Ideally any remaining old lunar water is poured out under the moon prior to charging another batch. This water is said to only retain its "virtue" from one full moon to the next.
Myth's Notes
There are several rituals for making lunar water, which is sometimes called moon water. This is a very basic method. The incantation mentioning Aradia is my addition, but it is very similar to other verbal blessings invoking a lunar spirit over the water. Another frequently used incantation for blessing the water was
Gracious Goddess, from the moon above,The title, "Gracious Goddess," is a Wiccan epithet of Aradia.
Fill this jar with magick and love.
Another method, which dates back to at least the early 1980's, of making moon water involved a large, clear, glass bowl. The symbol of Transformation was either etched on the outside of the bowl or written on a parchment and taped on the outside of the bowl. A silver coin or a silver moon-shaped medallion was heated thrice in a candle flame and dipped into the water. (The coin should make the water sizzle each time it's dipped.) The third time the silver piece was dipped, it was dropped in the water and left. As this method of making moon water was always performed at an esbat within a circle, a gate in the circle was then cut. The bowl of water was carried outside to catch the image of the moon reflected on the water. Three passes were then made with each hand over the water. No blessing was spoken, as this was a silent operation. The water was then carried back inside. It was eventually stored in a container for use during that month.
Lunar water could be used in place of spring water, for example, for a special bed-time blessing. It could also be used immediately to consecrate or charge items (see Transformation Symbol Charging Spell) or to simply sprinkle the altar. See Psychic Mint Tea for another method of making lunar water to be used in brewing a tea.