Hi Roger, I don’t know the chemistry. My main source of information was several years ago from a still manufacturer. I was asked to install a small distribution system from a still reservoir that pumped the water to the kitchen sink from the remote still location. The manufacturer and distributor were adamant that only plastic pipe could be used and they claimed that the copper would soon leak. The next time I speak with a still tech rep, I will ask. The soldering alloy will contain tin and antimony, but I don’t know the amounts. Back then, lead was still used in potable water piping. It would take a bit to time to look up the complete alloy. I think tin is less reactive, perhaps that is what could create the cell. My understanding is too limited to for me to make a meaningful comment. James-Osbourne: Holmes -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: Saturday, October 20, 2001 1:49 PM To: [email protected] Subject: CS>On the Corrosion of Copper in DW In a message dated 10/20/2001 12:23:41 AM Eastern Daylight Time, [email protected] writes:
Subj:CS>RE: Stainless dangerous? Date:10/20/2001 12:23:41 AM Eastern Daylight Time From: [email protected] (Kevin Nolan) Reply-to: [email protected] <mailto:[email protected]> To: [email protected] In Digest #951, James-Osbourne: Holmes wrote: "I use stainless cookware, and do all of my cooking with the same distilled water with which I make silver. I think it depends on a whole bunch of factors. I doubt very much if the leaching in practice is of any consequence whatsoever. "Copper is another story. DW dissolves it quite rapidly; such that you cannot use ordinary copper water tube for DW distribution. It will both perforate quickly---exactly how fast I don’t know—and put a lot of copper in the water. I suspect--but do not know---that it will put a potentially toxic amount of Cu into the water, depending on how much you drink. If one had a sensitive scale, you could put a chunk into DW and weigh it after it had been in there a while, constantly changing the water so that the dissolved copper would not slow down the process. The “Waterwise” still manufacturer may offer solid information about the various grades of SS. This would still not duplicate the process of running continuously fresh DW through a pipe." Some worthwhile advice there, James. Reminds me of a story run a few months back on TV here in Oz, about the huge cost of corrosion in copper water pipe. It's locale dependent but occurs all over the world. Apparently no-one has an answer as to why it happens or how to cure it (apart from replacing the pipe). Interestingly, there seemed to be a correlation between higher levels of dissolved iron picked up from ground water, and copper corrosion levels JOH: The interesting thing here is that a copper pipe (which I'll assume is 99.9+% copper) should NOT dissolve in DW because (unlike zinc, for example), it is less reactive than hydrogen. The only thing I can think of is that perhaps there is another, even more noble, metal in the vicinity so that a corrosion cell is set up. What relatively common metal is more noble than copper? Beats me. Roger
