I purchased a newly constructed home 15 months ago and have had an on-going issue of having dark gray/greenish particles come from both the hot and cold water lines. I've had the local water authority test the water and all parameters are within limits, but their analysis showed a tin level that is not consistent with the water authority. After a few months I was able to collect enough particles to have them tested. The analysis showed mostly tin, with some copper and other trace metals. I was told that it is common to have pieces of solder inside newly installed copper water piping and to flush the system. In addition to normal daily useage, I've flushed the system a few times by running all sinks, tubs, hoses at the same time for 15-20 minutes. Still I have the particles. Any ideas on what is causing this? Is this normal in new construction? Is it only a matter of time for everything to flush itself out or can I do something?