I often fill the kettle from the hot water tap in the hope that perhaps this will save some energy; however, if any of my friends are around whilst I am filling the kettle in this way, I am promptly told that the water from the hot tap is dirty and they certainly do not want tea made with this water. I then argue that the water will be boiled in the kettle, and that the spout of the kettle has a filter, so any nasty things will be killed or filtered out. My friends argue against this. Could I be wrong?