Source: {"pile_set_name": "USPTO Backgrounds"}

Cast copper alloy ingot CAC406, which has heretofore been used for parts of water supply systems and devices, contain 4.0 to 6.0% by weight of lead. Thus, lead in this material tends to dissolve into tap water. In order to reduce the amount of toxic lead that dissolves into tap water, consideration is now being given to developing lead-reduced or lead-free copper alloys.
But such lead-reduced or lead-free copper alloys are difficult to cast and cut, and also tend to be low in pressure resistance. Valves made of such alloys therefore tend to cause water leakage. Alloys are thus being considered that are not only low in lead content, but sufficiently high in pressure resistance and other necessary properties compared to alloys that are higher in lead content.
Among such alloys is one disclosed in Patent document 1, to which bismuth and selenium are added to improve machinability. Patent document 2 discloses an alloy to which silicon and magnesium are added to improve strength and leaching properties.
[Patent document 1] JP Patent publication 2004-68096A
[Patent document 2] JP patent publication 2004-52106A