What happened in Flint?

There is no doubt that high levels of lead were and continue to be present in the drinking water of Flint, Michigan.  What happened? 

Lead in drinking water comes from lead pipes, lead solder that joins copper pipes, and brass in faucets, coolers, valves.  It can also enter water from materials in old (say, older than 20 years) private wells, and older submersible pumps.  But the same pipes have been in the ground for years, so why is lead in Flint’s water now? 

When the city’s water source was switched to the Flint River, the pipes started to break down in a process called corrosion.  Rust is our most commonly known form of corrosion, and when corrosion occurs on iron, we call it rust.  Flint’s pipe network includes old lead pipes.  The switch from Lake Huron water to Flint River water caused unstable chemical conditions inside the pipes, such that the pipes started to degrade, releasing lead into the water. 

Many cities’ drinking water comes from rivers, and many have old pipes, so again, why is lead in Flint’s water?  Corrosion chemistry is complex but how to minimize it is fairly well understood; engineers often add anticorrosion chemicals to the water, to protect the pipes.  How much to add depends on “loop tests” but in the Flint case, there is no record that such testing was performed, and no anticorrosion chemicals were added.   Other data collected by city water officials indicated that corrosive conditions were occurring, but they did not use or act on those data

Engineers are obviously concerned when public infrastructure fails, and the Flint case highlights the important role of engineers in public health and safety. 

The University of Michigan College of Engineering is offering their expertise in this case, and has compiled commentary and video. 

blog what happened in flint largeCongressional committee hearings on March 17, 2016.

Sources:

Centers for Disease Control and Prevention.  2015.  Lead and drinking water from private wells.    July 1, 2015.  http://www.cdc.gov/healthywater/drinking/private/wells/disease/lead.html

Detroit News Staff.  2016.  How Flint’s water contamination crisis developed.  In The Detroit News.  February 2, 2016.  http://www.detroitnews.com/story/news/michigan/flint-water-crisis/2016/02/02/flints-water-contamination-crisis-developed/79736038/

Office of the Press Secretary, The White House.  2016.  President Obama signs Michigan emergency declaration.  January 16, 2016.  https://www.whitehouse.gov/the-press-office/2016/01/16/president-obama-signs-michigan-emergency-declaration

Olson, T.  2016.  The science behind the Flint water crisis: corrosion of pipes, erosion of trust.  In The Conversation.   January 28, 2016.  https://theconversation.com/the-science-behind-the-flint-water-crisis-corrosion-of-pipes-erosion-of-trust-53776

Torrice, M.  2016.  How lead ended up in Flint’s tap water.  In Chemical & Engineering News, Volume 94 Issue 7.  February 11, 2016.  http://cen.acs.org/articles/94/i7/Lead-Ended-Flints-Tap-Water.html

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