The purity and cleanliness of the water you choose is a personal choice. Cooking Soak the herbs. Place the herbs into the water. The water should cover the herbs by about an inch and a half. Let them sit for 15 minutes without turning on the heat beneath the teapot.
Some sources suggest allowing the herbs to absorb the room-temperature water for one hour.
Bring water to a rolling boil. Then, turn down the fire to a low simmer. Cook herbs for 20 to 30 minutes. There is a great deal of variation in the time necessary to cook herbs. It depends mostly on the kind of herbs you're cooking.