There is a specific concern of the laws of Biblical purity with regard to the copper laver, although the same problem can effect certain other vessels as well: anything left overnight in a sacred vessel becomes unfit for use in the morning. If water was left in the laver overnight, the priests would not be able to sanctify themselves with this water. Thus, the laver had to be emptied of its contents at the end of the day. But how could it be refilled quickly with enough water? In addition to this priest who officiates at the removal of the ashes, all 12 priests who will soon be offering the daily morning sacrifice must also wash their hands and feet at the laver!
Ben Katin, one of the High Priests who served during the era of the Second Temple, devised a system whereby this problem of ritual impurity can be circumvented: the mechanism of the muchni, meaning "machinery," or possibly derived from the word for "prepared." By emptying the laver of its contents from the previous day and then submerging in into a specially-made pool under the court, fresh water was obtained for the new day when the laver was hoisted up by the first priest in the morning - he who goes to remove the altar ashes. It was this sound of the laver being raised up with the muchni that could be heard by the other priests in the court, on the other side of the altar.