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6 sourced facts about plumbing, each with the context behind the number. 4 more are in today's round and appear here after it closes.
Answer4 or 5 years
Apprentices get about 2,000 hours of paid on-the-job training each year plus technical classes, and most states require plumbers to be licensed.
Source: U.S. Bureau of Labor Statistics, Occupational Outlook Handbook (2025) bls.gov
Answerlead (Latin plumbum)
A medieval plumber was 'a worker in any sort of lead' — roofs, gutters and pipes. It's also why lead's chemical symbol is Pb.
Source: Online Etymology Dictionary, plumber (2024) etymonline.com
Answernearly 30%
Toilets are by far the biggest indoor water user; old models can use as much as 6 gallons per flush.
Source: U.S. EPA WaterSense, Residential Toilets (2024) epa.gov
Answermore than 9,300 gallons
And 9% of homes have leaks that waste 50 gallons or more every day.
Source: U.S. EPA WaterSense, Fix a Leak Week (2025) epa.gov
Answer65%
Plumbing, heating and air-conditioning contractors are by far the biggest employer; only about 8% of these workers are self-employed.
Source: U.S. Bureau of Labor Statistics, Occupational Outlook Handbook (2025) bls.gov
Answer7%
That's much faster than average, with about 42,000 openings projected each year.
Source: U.S. Bureau of Labor Statistics, Occupational Outlook Handbook (2025) bls.gov