Water Quality
When brewing tea, it is very important to first ensure that you have a source of good, clean water.  Light-steamed Japanese tea is especially sensitive to water quality, and so any water impurities will noticeably alter the final flavor. We always recommend bringing the water to a full boil before brewing any of our teas. Boiling the water for around 3 minutes can significantly reduce the flavor of chemicals like chlorine.  Be careful not to boil the water for too long, though, or it will become flat and flavorless.  If possible, use soft water (with a low mineral content) to allow the leaves to infuse more fully.
Water Temperature
Next, it is critical to take note of the temperature of the water.  Japanese green teas can easily become bitter very quickly if they are steeped in water that is too hot.  If you do not wish to wait for your water to cool after boiling, you can pour some into a small pitcher, called a yuzamashi in Japanese, or into the serving cups.  Pouring the boiled water into cups to cool is a great way to ensure that you use the appropriate amount of water while also warming the cups enough that the tea will not cool too quickly after serving!