Larry, could you expand on this a little please.
It is my understanding that utilities will sometimes inject a small DC voltage between the steel piping and a sacraficial anode to ensure that the anode will electrolyse away instead of the steel pipe. On ocasions someone will inadvertantly reverse the polarity.
Back around 1990, a high end housing developement where Jose Conseco, the baseball player, lived when he was playing for Oakland, was suffering from blue water which was traced back to a miswired galvanic corrosion system.
So, when the gas piping bonding is disconnected from the building's ground system, AND a DC voltage is present, then a galvanic protection system is present, and it MIGHT be the cause of the blue water.