Great teas should always be made with fresh cold water which is heated. Unfortunately a lot of contradictory explanations can be found on the temperature of the water. We advise you not to boil your water (not even for black teas). When water boils oxygen will escape, which will flatten the taste of your tea. It is best to use an electric kettle on which the temperature is adjustable as every variety has its own ideal temperature.
The Dutch tapwater is – contrary to many other countries – suitable to drink directly from the tap. To purify the water even more you could consider a (carbon)filter. This reduces the amount of calcium, but also metals like lead and copper. Furthermore it intensifies the pure tastes of your tea.
Always make sure you pre-heat your teacup or pot with some hot tap water. This way not too much of the heat of your tea water will be drawn into the clay, porcelain, glass or metal of your cup or pot.