Orchids require very little water to survive. Generally you should water an orchid about once every seven days. Too much water will cause the plant's roots to rot.
Rain water is best for orchids. Tap water that has been treated with chemicals can be harsh on orchids. Unless you have a well, try to avoid using tap water to care for your plant.
If you live in a particularly hot or dry area of the country you may want to water your orchid twice a week.
Allow the water to run over the orchid for about 15 seconds. Afterwards, allow the plant to drain for about 15 minutes. You can set the plant in the kitchen sink to drain. Never place a tray under an orchid to collect water. Allowing the plant to sit in extra water is extremely harmful.
You want to use lukewarm water for this plant. Cold water can be very harmful and sometimes even fatal for an orchid.
Stick the tip of a sharpened pencil into the soil. If it turns darker in color, the plant has enough water.