Unintended consequences, that close cousin of mislaid plans, can claim some responsibility for a current conundrum: low-flow fixtures paired with existing oversized piping helped create the growing crisis of legionella bacteria.

It’s a reminder that our best intentions often blow up in our face. Take Braess’s paradox, for instance, the idea that if you add another motor lane to a congested route, with the intent of lessoning traffic, you end up increasing journey times. If you build it, they will come. It suggests that you could improve the malfunctioning system by removing certain aspects of it, not by adding to it.

A dissimilar yet equally entertaining (and instructional) example of unintended consequences in the digital era is expressed by the Streisand affect. When the actress and singer attempted to censor unflattering information about herself, she had the unintended consequence of publicizing it further and making the information more attractive than ever. In poetic terms, “The best-laid plans of mice and men often go awry.”

In the grand belly flopping history of human folly, the contemporary legionella tragedy rises somewhere above Marty McFly in “Back to the Future,” when he nearly dates his own mother and erases his existence, and below the assassination of an obscure archduke that triggered the first World War and our modern geopolitical condition. It’s awful, and it’s had devastating consequences, but it’s not the end of the world as we know it.

With proper planning and precaution, the industry can fix the problem. If we’re lucky, it could prove to be a blessing in disguise. No one wishes the pain and suffering caused by death and disease. But if good can be wrung from calamity, say, for instance, better cooperation between standards organizations, and revamping and modernizing of plumbing codes, then at least tragedy can serve some greater purpose. Perhaps the modernization of plumbing will prevent a worse, unforeseen disease of epidemic proportions that would have flourished if not for the red flags raised by Legionnaires’.

The inverse can also be true, and it makes me think of a passage in the latest Haruki Murakami novel, “Killing Commendatore.” In the book, a Japanese man tells his friend about the aforementioned English expression, explaining it as a “camouflaged blessing. A blessing that’s changed appearance. At first glance it seems unfortunate, but it turns out to bring you happiness.” He then adds, “There are things that should be the opposite, too, of course. In theory.”

In theory. Which brings us back to unintended consequences. As Tim Keane, owner of Legionella Risk Management, says in an article beginning on page 34 this month, “There are many opportunities for plumbing product technology, some new technology will have a huge impact on reducing legionella risk, while some will do the exact opposite.”

His point is that the industry should be sure that new water-safety products are motivated by health and science, and not profit. The same goes for the inevitable lobbying efforts that can shape code requirements and the mechanical world we live in.