Volunteered to supervise our building’s backflow inspection yesterday. What a fascinating distributed maintenance institution!
Big buildings have special valves to keep building water from being siphoned into the water supply. In SF, each has to be manually tested annually!
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Replying to
It’s a neat variation of “how many piano tuners in Chicago?”. There are a lot of condos in SF! 10^5 is probably the right order. Test took 30m; with transit maybe one plumber can do 10 tests per day. That’s ~2500 tests/year/plumber: ~40 full-time backflow testers!
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And that’s just residential—apparently the tests get more complex for commercial and industrial, since backflow may not only pollute but contaminate the water supply.
~*~maintenance.gif~*~
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Replying to
wait, so, that whole plot in Batman Begins about dumping a hallucinogen into the water supply could have been pulled off in any big apartment building??
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Does Gotham have wooden rooftop water tanks? If so, even easier.
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in my burb-house, we have to do annual backflow test to make sure hose/outdoor-sprinkler water doesn't wash back into house-water.
(possibly related: we're on well/septic, not municipal)
