A coil support member for attachment to a coil configured by a coiled tube placed inside a water storage vessel and which, because of multiple openings formed so as to be arranged in a line in a lengthwise direction and sites surrounding the openings, prevents contact between mutually adjacent loops of the tube of the coil and suppresses contact between an inner peripheral surface of the water storage vessel and an outer peripheral surface of the coil, the coil support member comprising: insertion portions that are formed between the openings that are mutually adjacent, with the insertion portions being inserted into an intra-coil space located further inward in a radial direction than the outer peripheral surface of the coil when the coil support member is attached to the coil; and a non-insertion portion that is positioned in an extra-coil space located further outward in the radial direction than the outer peripheral surface of the coil when the coil support member is attached to the coil, wherein the insertion portions have insertion body portions that prevent contact between mutually adjacent loops of the tube, characterized in that the insertion portions have engagement portions that project from the insertion body portions, contact the tube from the intra-coil space, and maintain the inserted state of the insertion body portions, the engagement portions including first engagement portions that project from one of the insertion body portions towards one side of the openings that are adjacent to both sides of that one insertion body portion and second engagement portions that project towards the other side. insertion portions that are formed between the openings that are mutually adjacent, with the insertion portions being inserted into an intra-coil space located further inward in a radial direction than the outer peripheral surface of the coil when the coil support member is attached to the coil; and a non-insertion portion that is positioned in an extra-coil space located further outward in the radial direction than the outer peripheral surface of the coil when the coil support member is attached to the coil, wherein the insertion portions have insertion body portions that prevent contact between mutually adjacent loops of the tube, characterized in that the insertion portions have engagement portions that project from the insertion body portions, contact the tube from the intra-coil space, and maintain the inserted state of the insertion body portions, the engagement portions including first engagement portions that project from one of the insertion body portions towards one side of the openings that are adjacent to both sides of that one insertion body portion and second engagement portions that project towards the other side. insertion body portions that prevent contact between mutually adjacent loops of the tube, characterized in that the insertion portions have engagement portions that project from the insertion body portions, contact the tube from the intra-coil space, and maintain the inserted state of the insertion body portions, the engagement portions including first engagement portions that project from one of the insertion body portions towards one side of the openings that are adjacent to both sides of that one insertion body portion and second engagement portions that project towards the other side. first engagement portions that project from one of the insertion body portions towards one side of the openings that are adjacent to both sides of that one insertion body portion and second engagement portions that project towards the other side.