Maybe blessing water?
The easiest way is to put it into a container (something special to you, preferably of a natural product like glass, clay pottery, wood, etc.) and take it outside under the full moon at night.
If you are unfamiliar witht basic Wiccan ritual, you will want to research "Grounding and Centering" and practice meditation. Traditionally a Wiccan might hold a small ritual to "Draw Down the Moon" into her own body first and direct the energy into the water.
An easier technique would be to set the water in a special place outdoors (a small temporary altar set up on a flat rock, a little table, a windowsill or even just nestled in some tree roots), meditate briefly and the ask out loud that the moon bless the water with her power. Ideally, you would then leave the water outside overnight and collect it again in the morning (if you're a stickler, just before sunrise).
Might you elaborate on what you're talking about? Are you talking about blessed water?
I'ld say bexvamcoot basically got that one covered if so.
Usually you want to take it out during a full moon or at least sit it on a window seal, for that type. There are different types of blessed water.
There's also spells in which can be used to purify the water, often salt may be used.
Another method is to put quartz crystal at the bottom of a container of water over night.
Combine all 3 if you so wish.
I'm sure there's numerous more. Don't be timid too look up ways yourself or even make your own way after studying varies methods.
You can make "Holy Water" under the full moon. Usually a little sea salt is added.
And how exactly do u do it? May I ask