Before antibiotics, before germ theory was even accepted, the thing that stopped cities from poisoning their own people was pipe — laid by the trade this article is about.
When water was the killer
Cholera swept North American cities repeatedly through the 1800s — the 1832 and 1849 epidemics killed thousands in New York, Montreal, and cities along the rivers. Nobody fully understood why until London physician John Snow traced an 1854 outbreak to a single contaminated water pump on Broad Street. The lesson took decades to absorb, but it changed what cities were: clean water in, waste out, and never the two touching.
That work didn't belong to doctors. It belonged to plumbers.
Building the sanitary city
Through the late 1800s and early 1900s, North American cities built water and sewer systems at staggering scale, and the plumbing trade professionalized alongside them:
- 1889 — the United Association (UA) was founded, uniting plumbers, steamfitters, and pipefitters across the US and Canada.
- Early plumbing codes followed, city by city, standardizing traps, venting, and backflow protection — the invisible details that keep sewage and drinking water permanently separated.
- The 20th century brought indoor plumbing from luxury to baseline: in 1940 nearly half of US homes still lacked complete plumbing; within two generations that number fell to almost nothing.
Public-health historians routinely rank clean water and sanitation among the greatest life-savers in human history — ahead of most medical interventions. That ranking is the plumbing trade's monument.
The same fight, modern form
Every trap, vent, cross-connection rule, and backflow preventer in today's plumbing codes is a cholera lesson written into law. Codes differ by jurisdiction — our code lookup tracks which plumbing code each US state and Canadian province currently enforces.
And the trade the sanitarians built is still hiring: plumbers logged 189 new postings in our August 2026 Hiring Index, with US postings that disclosed pay running a median of $78,000/year. In Canada, plumbing remains a compulsory certification trade in most provinces, with the Red Seal as the interprovincial standard.
Join the lineage
- Browse plumbing jobs — live openings across the US and Canada
- Plumber pay data — what the trade earns now
- Hiring Index — the monthly state of trades hiring