I read somewhere that some of the new copper pipe has a lot more impurities in it than the old pipe did, so it goes bad quicker. Also do not over do it with the flux, it keeps the green layer from growing inside the pipe and that is what helps to protect the pipe from electrolysis. Some plumbers are in the habit of dipping the pipe into the flux can, use a brush. You have to get a nice layer on the pipe and fitting, but don't go overboard.
The electrical codes require the copper pipes to be grounded, but it is bad for the pipe, but very necessary. Use PEX pipe it will last about as long if properly installed, the electricians will stay away from it.
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