<P> Generally, copper tubes are soldered directly into copper or brass fittings, although compression, crimp, or flare fittings are also used . Formerly, concerns with copper supply tubes included the lead used in the solder at joints (50% tin and 50% lead). Some studies have shown significant "leaching" of the lead into the potable water stream, particularly after long periods of low usage, followed by peak demand periods . In hard water applications, shortly after installation, the interior of the pipes will be coated with the deposited minerals that had been dissolved in the water, and therefore the vast majority of exposed lead is prevented from entering the potable water . Building codes throughout the U.S. require the use of virtually "lead - free" (<0.2% lead) solder or filler metals in plumbing fittings and appliances . </P> <P> Copper water tubes are susceptible to cold water pitting caused by contamination of the pipe interior, typically with soldering flux; erosion corrosion caused by high speed or turbulent flow; and stray current corrosion, caused by poor electrical wiring technique, such as improper grounding and bonding . </P> <P> Pinhole leaks with pitting initiating on the exterior surface of the pipe, can occur if copper piping is improperly grounded or bonded . The phenomenon is known technically as stray current corrosion or electrolytic pitting . Pin - holing due to poor grounding or poor bonding occurs typically in homes where the original plumbing has been modified; homeowners may find that a new plastic water filtration device or plastic repair union has interrupted the water pipe's electrical continuity to ground, when they start seeing pinhole water leaks after a recent install . Damage occurs rapidly, usually becoming obvious about six months after the ground interruption . Correctly installed plumbing appliances will have a copper bonding jumper cable connecting the interrupted pipe sections . Pinhole leaks from stray current corrosion can result in high plumbing bills and require the replacement of the entire water line . The cause is fundamentally an electrical defect, not a plumbing defect; once the plumbing damage is repaired, an electrician should promptly be consulted to evaluate the grounding and bonding of the entire plumbing and electrical systems . </P> <P> The difference between a ground and a bond is subtle . See Ground, for a complete description . </P>

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