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Galvanized pipe is zinc coated steel. There is generally no lead in a galvanized pipe. For more information on this topic, see https://www.dcwater.com/waterquality/plumbing/faq.cfm.
Problems arise because over time, the zinc coating on the pipes breaks down, and the steel rusts. This occurs more rapidly in corrosive water, which may be due to acidity of the water, or minerals in the water. Once the pipe starts to break down, various issues arise such as loss of flow, reduced pressure, and formation of internal clogs that can collect lead from incoming city water mains (yes, many cities still have lead pipes for water delivery).
In the case of Flint, the city changed water supply from Lake Huron to the Flint River in an effort to save money. The Flint River has corrosive water, primarily due to iron content, and as a result the city water pipes, some of which are apparently made of lead, started to leach lead into the water system. I would not be surprised to find out that many of the houses in Flint have copper water supply pipe that use 50-50 lead/tin solder joints, and the joints may have leached lead into the house water, contributing to the problem.
You can read a decent summary of the issues in Flint here http://www.cnn.com/2016/01/11/health/toxic-tap-water-flint-michigan/.
I had to replace some galvanized pipe in my house, along with all the copper pipe, about 15 years ago due to my acidic well water. The options were to treat the water to make it less acidic, or replace the pipe with PEX, which is inert to acidic water. The pipes were all deteriorated (pin hole leaks, corrosion) so I simply replaced all the pipe. But I suspect that prior to my replacement, I was probably leaching lead from the solder joints. Modern copper solder is 95% tin, 5% antimony. I have no idea if antimony is leached into water, and I don't know if it is toxic. Similarly I don't know if the tin is OK. Seems we find out about problems long after the fact.
Problems arise because over time, the zinc coating on the pipes breaks down, and the steel rusts. This occurs more rapidly in corrosive water, which may be due to acidity of the water, or minerals in the water. Once the pipe starts to break down, various issues arise such as loss of flow, reduced pressure, and formation of internal clogs that can collect lead from incoming city water mains (yes, many cities still have lead pipes for water delivery).
In the case of Flint, the city changed water supply from Lake Huron to the Flint River in an effort to save money. The Flint River has corrosive water, primarily due to iron content, and as a result the city water pipes, some of which are apparently made of lead, started to leach lead into the water system. I would not be surprised to find out that many of the houses in Flint have copper water supply pipe that use 50-50 lead/tin solder joints, and the joints may have leached lead into the house water, contributing to the problem.
You can read a decent summary of the issues in Flint here http://www.cnn.com/2016/01/11/health/toxic-tap-water-flint-michigan/.
I had to replace some galvanized pipe in my house, along with all the copper pipe, about 15 years ago due to my acidic well water. The options were to treat the water to make it less acidic, or replace the pipe with PEX, which is inert to acidic water. The pipes were all deteriorated (pin hole leaks, corrosion) so I simply replaced all the pipe. But I suspect that prior to my replacement, I was probably leaching lead from the solder joints. Modern copper solder is 95% tin, 5% antimony. I have no idea if antimony is leached into water, and I don't know if it is toxic. Similarly I don't know if the tin is OK. Seems we find out about problems long after the fact.
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I think the lead came from the pipes because the chemicals in the river water dissolved them better than the Detroit water.
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Ayuh,... The pipes are copper, the solder used to join 'em had lead in it, til the '80s or so,....
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And do we know what percent zinc / lead the alloy was at the time of galvanization. Without strict controls we can be assured if lead was less expensive than zinc then more lead was added.
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Copper pipes commonly use solder to join pieces together. As noted by others, up until the 1980's the solder was a 50/50 mix of tin and lead. I still have some old 50/50 solder in my basement. Eventually the solder transitioned to lead free, which is 95 percent tin, 5 percent antimony, which is the current copper pipe solder sold.
Galvanized pipe is typically joined by threading, there is no solder used, so if you have galvanized pipe in your house, you will not leach lead out. You will definitely leach zinc out, since the steel pipe is coated with zinc (the galvanization metal).
The Flint River water did not test positive for lead, that was never the issue. The issue is that the Flint River water is more corrosive to pipes than the Lake Huron water that Flint used to purchase from Detroit. The additional corrosivity of the Flint River water leached lead out of City of Flint lead water supply pipes, and perhaps leached lead out of the solder joints in houses that used copper pipe for water supply (probably most of the houses in Flint).
As a note, many municipalities have lead water supply pipes, and continue to use them. I worked on several Boston water supply project, and Boston still has some in use lead pipes, and some wooden ones as well. It is very expensive to replace water pipes, and of course infrastructure is chronically underfunded, so municipalities try to stretch the life of pipes to the end.
Galvanized pipe is typically joined by threading, there is no solder used, so if you have galvanized pipe in your house, you will not leach lead out. You will definitely leach zinc out, since the steel pipe is coated with zinc (the galvanization metal).
The Flint River water did not test positive for lead, that was never the issue. The issue is that the Flint River water is more corrosive to pipes than the Lake Huron water that Flint used to purchase from Detroit. The additional corrosivity of the Flint River water leached lead out of City of Flint lead water supply pipes, and perhaps leached lead out of the solder joints in houses that used copper pipe for water supply (probably most of the houses in Flint).
As a note, many municipalities have lead water supply pipes, and continue to use them. I worked on several Boston water supply project, and Boston still has some in use lead pipes, and some wooden ones as well. It is very expensive to replace water pipes, and of course infrastructure is chronically underfunded, so municipalities try to stretch the life of pipes to the end.
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That was a smart decision to save money on the part of Flint....
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Ayuh,.... 'n mighty friendly of neighborin' Detroit to tryin' Over-charge Flint for the water they were usin',....
Flint really had no choice, other than go broke with Detroit, or use they're backup system til the new pipeline is built,....
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