Could the copper issue be coming from the hot water tank and not actually the pipes? I was just thinking about this today. My in-laws had copper erosion in their pipes to the point where they burst leaks and they had to replace all pipes with plastic. But there was never a blue stain in their sinks. Here, it's all I can do to keep the blue stain down, especially in the bathroom upstairs where mostly hot water is used naturally. My in laws had an oil furnace so they didn't have a tank with a copper anode, but here I have an electric hot water tank. Could much of my copper issue be coming from the hot water tank and not actually the pipes? I mean, it's probably coming from the pipes too, but I can correct this by running the water a long time before I fill buckets for the tank. But if it's coming from the hot water tank, it won't matter how long I run it unless I actually go to the point of emptying the tank (which would be self-defeating), unless I use cold water. Is there any way I can easily test water for copper?