Storage and Use for Your Holy Water
Where to get it
To get holy water to use in your home, bring a clean flask to your parish church and look for a faucet or an urn that will probably be labelled "Holy Water." If you can't find it, don't be shy; just ask! There is no real cost to the church in making holy water, so there is no offering expected.
How to use it
You can keep it in decorative bottles for storage at home or in little flasks, made for this purpose, to carry with you. Most Catholics keep at least some in holy water fonts which come in all sizes and shapes. Lovely ones can be made of alabaster, marble, porcelain, sandstone, or metals -- as inexpensive or as expensive as you like -- some resting on tables, most hanging on walls. Tip: putting a thin sponge inside the font is said to make the water evaporate less quickly.
Catholics often keep a font near their front door, in their bedrooms' doorways, or near the family altar. Use the water in the same way you do at church, dipping your fingers into it and making the Sign of the Cross. Bless your children with it as you tuck them in at night, using your thumb to sign them with a cross of holy water on their foreheads.
Most Catholics pray "In the Name of the Father, and of the Son, and of the Holy Ghost" when blessing themselves with Holy Water, but another beautiful prayer is:
By Thy Precious Blood and by this Holy Water, cleanse me (him/her) from my (his/her) sins, O Lord.
Another use of holy water is to give tiny sips to the sick or spiritually oppressed. It shouldn't be consumed as a beverage, but the ingestion of small amounts, or adding a few drops to foods, is common.
How to dispose of
Holy water is usually made with a touch of salt which is a preservative, but if your holy water were to go a little, um, green, the proper way to dispose of it is the same as for any sacramental: you want to return it to the earthly elements. You should dig a hole and pour it into the earth.
Adapted from The Catholic Encyclopedia