# Plumbers, Pipefitters, and Steamfitters

US SOC code 47-2152. Markdown version of https://futurehistory.earth/timeline/47-2152

Also called: Plumber, Pipefitter, Steamfitter, Residential plumber, Service plumber.

## In brief

In May 2025, [BLS](https://www.bls.gov/oes/special-requests/oesm25nat.zip) counted **465,840** US plumbers, pipefitters, and steamfitters, with median pay of **$63,800** a year. Of the BLS counts since 2003, the May 2025 count is the highest. The earliest figure here is [a Census count](https://usa.ipums.org/usa/volii/9050occup.shtml) of **102,000** from 1900, not measured the same way as today's count. The last full technology era for plumbers, pipefitters, and steamfitters: Smart water monitoring + BIM coordination + Flint crisis aftermath, 2012 to 2021.

## What the sources say

### Official outlook

BLS projects employment to grow 6.8% from 2025 to 2035. Source: [BLS Employment Projections 2025-35](https://data.bls.gov/projections/nationalMatrix?queryParams=47-2152&ioType=o).

### AI exposure studies

- **5.6%** of this job's tasks are exposed to large language models. Not a forecast of job losses. [Eloundou and others, 2023](https://github.com/openai/GPTs-are-GPTs/blob/main/data/occ_level.csv)
- **0.35** estimated probability that the whole occupation could be computerised, over an unspecified number of years. Not a forecast of job losses. [Frey and Osborne, 2013](https://oms-www.files.svdcdn.com/production/downloads/academic/The_Future_of_Employment.pdf)

### Since the 2013 prediction

In 2013, Frey and Osborne put this job's probability of computerisation at 0.35. BLS counted **351,380** of these jobs in May 2013 and **465,840** in May 2025 (+33%, a change derived by Future History).

Data as of BLS OEWS May 2025; BLS Employment Projections 2025-35. BLS publishes these counts as yearly survey snapshots and cautions against reading them as a precise trend. In May 2021 BLS changed how it estimates these counts (a model-based method using three years of survey data) and moved fully to the 2018 occupation codes, so part of a change across 2021 can come from the method rather than the work.

## Plumbers, Pipefitters, and Steamfitters employment and pay by year

- On record since: 1849
- Latest US employment: 465,840 (May 2025). Source: BLS OEWS May 2025 [6]
- Latest US median pay: $63,800 (May 2025). Source: BLS OEWS May 2025 [16]
- Outlook: +6.8% by 2035. Source: BLS Employment Projections 2025-35 [39]

### In other countries

The latest figure each country's statistics agency publishes for this job. Each uses its own occupation definition, survey basis and currency, so the numbers are not directly comparable with each other or with the US figures.

- **Canada** (NOC 72300)
  - Employment, 2020: 71,440. Source: Statistics Canada Census 2021 [9]. Statistics Canada Census of Population 2021: number of persons with employment income, the EXACT SUM of the cited cells for NOC 72300 + 72301 (this US occupation has no single NOC unit-group equivalent), combined as Plumbers, steamfitters and pipefitters, Canada, reference year 2020. A recipients basis (anyone with employment income during the year), slightly broader than a point-in-time employed count. A sum of cited cells, not an estimate. Statistics Canada Open Licence.
  - Median pay, 2020: C$63,600. Source: Statistics Canada Census 2021 [20]. Statistics Canada Census of Population 2021 (Table 98-10-0586): median employment income for NOC 72300 Plumbers, the dominant constituent of the combined Plumbers, steamfitters and pipefitters (NOC 72300 + 72301), Canada, reference year 2020, full-year full-time workers (the basis comparable to the US OEWS full-time median). This is the cited median of the dominant group, not a blend of the constituent medians. Statistics Canada Open Licence.
- **United Kingdom** (UK SOC 5315)
  - Employment, 2025: 58,000. Source: ONS ASHE 2025 [12]. ONS Annual Survey of Hours and Earnings (Table 14): employee jobs in SOC 5315 Plumbers & heating and ventilating installers and repairers, United Kingdom, 2025 (ASHE "number of jobs", thousands x1000; excludes self-employment). Open Government Licence v3.0.
  - Median pay, 2025: £36,563. Source: ONS ASHE 2025 [23]. ONS Annual Survey of Hours and Earnings (Table 14.7a): median gross annual pay for all employee jobs in SOC 5315 Plumbers & heating and ventilating installers and repairers, United Kingdom, 2025. Open Government Licence v3.0.
- **Australia** (ANZSCO 3341)
  - Employment, 2025: 108,500. Source: ABS Labour Force Survey [13]. ABS Labour Force Survey (Detailed), table EQ08: employed persons in ANZSCO 3341 Plumbers, national (summed across sex and state/territory), annual average of 4 quarterly estimates.
  - Median pay, 2025: A$103,480. Source: ABS Employee Earnings May 2025 [24]. Annualised (x52) from A$1,990 median weekly earnings. ABS Survey of Employee Earnings and Hours, May 2025: median pay for full-time non-managerial employees paid at the adult rate, before tax. Surfaced via the Jobs and Skills Australia occupation profile.

### All 29 years of cited US data

| Year | US employment | Annual pay (median unless marked) | Source |
| --- | --- | --- | --- |
| 1900 | 102,000 | n/a | Decennial Census 1900 [1] |
| 1920 | 168,000 (estimate) | n/a | Est., Estimate for 1920 (~168,000) [2] |
| 1940 | 189,000 (estimate) | n/a | Est., Wikipedia [3] |
| 1960 | 310,000 (estimate) | n/a | Est., BLS Occupational Outlook Handbook [4] |
| 1980 | 430,000 (estimate) | $19,000 (estimate) | Est., BLS Occupational Outlook Handbook [4] |
| 2000 | 437,140 | $37,840 | BLS OEWS 2000 [5] |
| 2003 | 433,600 | $40,950 | BLS OEWS May 2003 [6] |
| 2004 | 424,360 | $41,290 | BLS OEWS May 2004 [6] |
| 2005 | 420,770 | $42,160 | BLS OEWS May 2005 [6] |
| 2006 | 435,960 | $42,770 | BLS OEWS May 2006 [6] |
| 2007 | 435,010 | $44,090 | BLS OEWS May 2007 [6] |
| 2008 | 437,540 | $45,640 | BLS OEWS May 2008 [6] |
| 2009 | 400,970 | $46,320 | BLS OEWS May 2009 [6] |
| 2010 | 358,790 | $46,660 | BLS OEWS May 2010 [6] |
| 2011 | 349,320 | $47,750 | BLS OEWS May 2011 [6] |
| 2012 | 340,370 | $49,140 | BLS OEWS May 2012 [6] |
| 2013 | 351,380 | $50,180 | BLS OEWS May 2013 [6] |
| 2014 | 372,570 | $50,660 | BLS OEWS May 2014 [6] |
| 2015 | 391,680 | $50,620 | BLS OEWS May 2015 [6] |
| 2016 | 411,870 | $51,450 | BLS OEWS May 2016 [6] |
| 2017 | 428,260 | $52,590 | BLS OEWS May 2017 [6] |
| 2018 | 438,070 | $53,910 | BLS OEWS May 2018 [6] |
| 2019 | 442,870 | $55,160 | BLS OEWS May 2019 [6] |
| 2020 | 417,440 | $56,330 | BLS OEWS May 2020 [6] |
| 2021 | 417,620 | $59,880 | BLS OEWS May 2021 [6] |
| 2022 | 427,920 | $60,090 | BLS OEWS May 2022 [6] |
| 2023 | 436,160 | $61,550 | BLS OEWS May 2023 (employment) [6]; BLS OEWS May 2023 (pay) [17] |
| 2024 | 455,940 | $62,970 | BLS OEWS May 2024 [6] |
| 2025 | 465,840 | $63,800 | BLS OEWS May 2025 [6] |

## Sources (116)

### Employment series

1. [IPUMS USA — 1900 Census occupational data; "plumbers and pipe fitters" occupation category (Historical Statistics of the United States)](https://usa.ipums.org/usa/volii/9050occup.shtml), IPUMS / University of Minnesota
2. [Estimate for 1920 (~168,000), anchored by the 1920 Census occupation total and United Association membership records; the direct 1920 Census figure for 'Plumbers and gas and steam fitters' was 206,718](https://ua.org/about-the-ua/), Future History (estimate)
3. [Wikipedia — "United Association" (membership milestones: 60,000 in 1940, 240,000 by 1954; 1936 apprenticeship plan)](https://en.wikipedia.org/wiki/United_Association), Wikipedia (citing UA historical records)
4. [BLS Occupational Outlook Handbook — Plumbers, Pipefitters, and Steamfitters (historical employment summary; post-war construction boom context)](https://www.bls.gov/ooh/construction-and-extraction/plumbers-pipefitters-and-steamfitters.htm), Bureau of Labor Statistics
5. [BLS OES 2000 national estimates (flat file)](https://www.bls.gov/oes/special-requests/oes00nat.zip), Bureau of Labor Statistics
6. BLS OEWS, national cross-industry estimates (flat file), Bureau of Labor Statistics. Editions: [2003](https://www.bls.gov/oes/special-requests/oesm03nat.zip), [2004](https://www.bls.gov/oes/special-requests/oesm04nat.zip), [2005](https://www.bls.gov/oes/special-requests/oesm05nat.zip), [2006](https://www.bls.gov/oes/special-requests/oesm06nat.zip), [2007](https://www.bls.gov/oes/special-requests/oesm07nat.zip), [2008](https://www.bls.gov/oes/special-requests/oesm08nat.zip), [2009](https://www.bls.gov/oes/special-requests/oesm09nat.zip), [2010](https://www.bls.gov/oes/special-requests/oesm10nat.zip), [2011](https://www.bls.gov/oes/special-requests/oesm11nat.zip), [2012](https://www.bls.gov/oes/special-requests/oesm12nat.zip), [2013](https://www.bls.gov/oes/special-requests/oesm13nat.zip), [2014](https://www.bls.gov/oes/special-requests/oesm14nat.zip), [2015](https://www.bls.gov/oes/special-requests/oesm15nat.zip), [2016](https://www.bls.gov/oes/special-requests/oesm16nat.zip), [2017](https://www.bls.gov/oes/special-requests/oesm17nat.zip), [2018](https://www.bls.gov/oes/special-requests/oesm18nat.zip), [2019](https://www.bls.gov/oes/special-requests/oesm19nat.zip), [2020](https://www.bls.gov/oes/special-requests/oesm20nat.zip), [2021](https://www.bls.gov/oes/special-requests/oesm21nat.zip), [2022](https://www.bls.gov/oes/special-requests/oesm22nat.zip), [2023](https://www.bls.gov/oes/special-requests/oesm23nat.zip), [2024](https://www.bls.gov/oes/special-requests/oesm24nat.zip), [2025](https://www.bls.gov/oes/special-requests/oesm25nat.zip)
7. [Statistics Canada, Census of Population 2006, Table 97-563-XCB2006069 (Wage and salary statistics by occupation, NOC-S 2006), income reference year 2005](https://www12.statcan.gc.ca/census-recensement/2006/dp-pd/tbt/Rp-eng.cfm?LANG=E&PID=96285), Statistics Canada
8. [Statistics Canada, Census of Population 2016, Table 98-400-X2016356 (Occupation by employment income statistics, NOC 2016), income reference year 2015](https://www150.statcan.gc.ca/n1/en/catalogue/98-400-X2016356), Statistics Canada
9. [Statistics Canada, Census of Population 2021, Table 98-10-0586 (Employment income statistics by occupation unit group, NOC 2021), income reference year 2020](https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=9810058601), Statistics Canada
10. ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 5314, United Kingdom. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0., Office for National Statistics. Editions: [2002](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2002/2002-table-14.zip), [2006](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2006consistentw_007methodology/2006-table-14.zip), [2010](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2010revised/2010-revised-table-14.zip), [2011](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2011revisedbasedonsoc2010/2011-revised-table-14.zip), [2015](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2015/table142015revised.zip), [2020](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2020revised/table142020revised.zip)
11. [ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 5315, United Kingdom, 2022. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0.](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2022revised/ashetable142022revised.zip), Office for National Statistics
12. [ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 5315, United Kingdom, 2025. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0.](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2025provisional/ashetable142025provisional.zip), Office for National Statistics
13. [ABS: Labour Force, Australia, Detailed, table EQ08 (Employed persons by Occupation unit group, ANZSCO 2013), latest release](https://www.abs.gov.au/statistics/labour/employment-and-unemployment/labour-force-australia-detailed/latest-release), Australian Bureau of Statistics

### Wage series

14. [BLS Occupational Outlook Handbook — Plumbers, Pipefitters, and Steamfitters (1980-81 edition wage context); inflation adjustment via BLS CPI-U calculator](https://www.bls.gov/ooh/construction-and-extraction/plumbers-pipefitters-and-steamfitters.htm), Bureau of Labor Statistics
15. [BLS OES 2000 national estimates (flat file)](https://www.bls.gov/oes/special-requests/oes00nat.zip), Bureau of Labor Statistics
16. BLS OEWS, national cross-industry estimates (flat file), Bureau of Labor Statistics. Editions: [2003](https://www.bls.gov/oes/special-requests/oesm03nat.zip), [2004](https://www.bls.gov/oes/special-requests/oesm04nat.zip), [2005](https://www.bls.gov/oes/special-requests/oesm05nat.zip), [2006](https://www.bls.gov/oes/special-requests/oesm06nat.zip), [2007](https://www.bls.gov/oes/special-requests/oesm07nat.zip), [2008](https://www.bls.gov/oes/special-requests/oesm08nat.zip), [2009](https://www.bls.gov/oes/special-requests/oesm09nat.zip), [2010](https://www.bls.gov/oes/special-requests/oesm10nat.zip), [2011](https://www.bls.gov/oes/special-requests/oesm11nat.zip), [2012](https://www.bls.gov/oes/special-requests/oesm12nat.zip), [2013](https://www.bls.gov/oes/special-requests/oesm13nat.zip), [2014](https://www.bls.gov/oes/special-requests/oesm14nat.zip), [2015](https://www.bls.gov/oes/special-requests/oesm15nat.zip), [2016](https://www.bls.gov/oes/special-requests/oesm16nat.zip), [2017](https://www.bls.gov/oes/special-requests/oesm17nat.zip), [2018](https://www.bls.gov/oes/special-requests/oesm18nat.zip), [2019](https://www.bls.gov/oes/special-requests/oesm19nat.zip), [2020](https://www.bls.gov/oes/special-requests/oesm20nat.zip), [2021](https://www.bls.gov/oes/special-requests/oesm21nat.zip), [2022](https://www.bls.gov/oes/special-requests/oesm22nat.zip), [2024](https://www.bls.gov/oes/special-requests/oesm24nat.zip), [2025](https://www.bls.gov/oes/special-requests/oesm25nat.zip)
17. [BLS OEWS May 2023 — 47-2152 Plumbers, Pipefitters, and Steamfitters (median annual wage ~$61,550; ~$29.59/hr)](https://www.bls.gov/oes/2023/may/oes472152.htm), Bureau of Labor Statistics
18. [Statistics Canada, Census of Population 2006, Table 97-563-XCB2006069 (Wage and salary statistics by occupation, NOC-S 2006), income reference year 2005](https://www12.statcan.gc.ca/census-recensement/2006/dp-pd/tbt/Rp-eng.cfm?LANG=E&PID=96285), Statistics Canada
19. [Statistics Canada, Census of Population 2016, Table 98-400-X2016356 (Occupation by employment income statistics, NOC 2016), income reference year 2015](https://www150.statcan.gc.ca/n1/en/catalogue/98-400-X2016356), Statistics Canada
20. [Statistics Canada, Census of Population 2021, Table 98-10-0586 (Employment income statistics by occupation unit group, NOC 2021), income reference year 2020](https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=9810058601), Statistics Canada
21. ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 5314, United Kingdom. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0., Office for National Statistics. Editions: [2002](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2002/2002-table-14.zip), [2006](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2006consistentw_007methodology/2006-table-14.zip), [2010](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2010revised/2010-revised-table-14.zip), [2011](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2011revisedbasedonsoc2010/2011-revised-table-14.zip), [2015](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2015/table142015revised.zip), [2020](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2020revised/table142020revised.zip)
22. [ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 5315, United Kingdom, 2022. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0.](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2022revised/ashetable142022revised.zip), Office for National Statistics
23. [ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 5315, United Kingdom, 2025. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0.](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2025provisional/ashetable142025provisional.zip), Office for National Statistics
24. [Jobs and Skills Australia: Plumbers (ABS Survey of Employee Earnings and Hours, May 2025)](https://www.jobsandskills.gov.au/data/occupation-and-industry-profiles/occupations/3341-plumbers), Jobs and Skills Australia / Australian Bureau of Statistics

### Tool eras

25. [IPUMS USA — 1900 Census occupational data; plumbers and pipe fitters category (Historical Statistics of the United States)](https://usa.ipums.org/usa/volii/9050occup.shtml), IPUMS / University of Minnesota
26. [United Association — "About the UA" (135-year history since 1889 founding; plumbers, gas fitters, steam fitters)](https://ua.org/about-the-ua/), United Association
27. [Wikipedia — "United Association" (1921 mandatory five-year apprenticeship, 1936 National Plumbing Apprenticeship Plan)](https://en.wikipedia.org/wiki/United_Association), Wikipedia (citing UA historical records)
28. [Copper Development Association — "History of Copper in Plumbing" (copper tube adoption 1930s onward, residential standard)](https://copper.org/applications/plumbing/), Copper Development Association
29. [IAPMO — "2027 UPC/UMC Publication" (UPC introduced in Los Angeles in 1928, formally published as the Uniform Plumbing Code in 1945)](https://www.iapmo.org/newsroom/press-releases/iapmo-publishes-2027-editions-of-upc-umc), International Association of Plumbing and Mechanical Officials
30. [Plastics Pipe Institute — Building & Construction Division (plastic pressure pipe for plumbing, water service, and hydronic systems)](https://plasticpipe.org/buildingconstruction), Plastics Pipe Institute
31. [US EPA — "Overview of the Safe Drinking Water Act" (SDWA originally passed by Congress in 1974; amended 1986 and 1996)](https://www.epa.gov/sdwa/overview-safe-drinking-water-act), US Environmental Protection Agency
32. [Wikipedia — "Cross-linked polyethylene" (PEX used in hydronic systems from 1960s; increasingly replacing copper in residential plumbing since the 2000s)](https://en.wikipedia.org/wiki/Cross-linked_polyethylene), Wikipedia
33. [HammerHead Trenchless — Products (CIPP lateral and main line rehabilitation, pipe bursting, pipe slitting, pipe ramming)](https://www.hammerheadtrenchless.com/products/), HammerHead Trenchless
34. [Wikipedia — "Flint water crisis" (April 25, 2014 trigger; 3,500 lead lines in Flint; national lead service line context)](https://en.wikipedia.org/wiki/Flint_water_crisis), Wikipedia (citing EPA, Michigan DEQ, and peer-reviewed sources)
35. [Wikipedia — "Lead and Copper Rule" (1991 original rule; October 2024 revision mandating 10-year replacement; EPA annual cost estimate $1.5-2B)](https://en.wikipedia.org/wiki/Lead_and_Copper_Rule), Wikipedia (citing EPA regulatory text)
36. [Wikipedia — "Infrastructure Investment and Jobs Act" (IIJA November 2021; $15B lead service line replacement; $11.7B Drinking Water SRF; total water provisions ~$55B)](https://en.wikipedia.org/wiki/Infrastructure_Investment_and_Jobs_Act), Wikipedia (citing White House, CBO, and EPA sources)
37. [BLS National Employment Matrix — 47-2152 Plumbers, Pipefitters, and Steamfitters (2024-34 projections: 504,500 baseline, 527,200 projected)](https://data.bls.gov/projections/nationalMatrix?queryParams=47-2152&ioType=o), Bureau of Labor Statistics
38. [US Department of Energy — "Heat Pump Water Heaters" (installation requirements, IRA credit context, professional installation)](https://web.archive.org/web/20260630092818/https://www.energy.gov/energysaver/heat-pump-water-heaters), US Department of Energy (via Wayback Machine snapshot, original 404)

### Forecasts and exposure studies

39. [BLS Employment Projections 2025-35, National Employment Matrix: 47-2152 Plumbers, pipefitters, and steamfitters (2025: 510.6 thousand; 2035: 545.2 thousand; +6.8%)](https://data.bls.gov/projections/nationalMatrix?queryParams=47-2152&ioType=o), Bureau of Labor Statistics
40. [Frey & Osborne (2013), "The Future of Employment: How Susceptible Are Jobs to Computerisation?", Appendix (SOC 47-2152 Plumbers, Pipefitters, and Steamfitters: probability 0.35, rank 249 of 702)](https://oms-www.files.svdcdn.com/production/downloads/academic/The_Future_of_Employment.pdf), Oxford Martin School, University of Oxford
41. [Eloundou, Manning, Mishkin & Rock (2023), "GPTs are GPTs", occupation-level exposure data occ\_level.csv (O\*NET-SOC 47-2152.00, human-rated β 0.056)](https://github.com/openai/GPTs-are-GPTs/blob/main/data/occ_level.csv), OpenAI

### Historical notes

42. [IAPMO — "2027 UPC/UMC Publication" (UPC introduced in Los Angeles in 1928, formally published as the Uniform Plumbing Code in 1945)](https://www.iapmo.org/newsroom/press-releases/iapmo-publishes-2027-editions-of-upc-umc), International Association of Plumbing and Mechanical Officials
43. [Wikipedia — "United Association" (October 11, 1889 founding; original and current names; 400,000 current members)](https://en.wikipedia.org/wiki/United_Association), Wikipedia (citing UA historical records)
44. [Wikipedia — "Safe Drinking Water Act" (December 16, 1974 enactment; 1986 amendments banning lead solder; EPA contaminant regulation authority)](https://en.wikipedia.org/wiki/Safe_Drinking_Water_Act), Wikipedia (citing US EPA and Federal Register)
45. [Wikipedia — "Flint water crisis" (April 25, 2014 crisis trigger; 3,500 lead lines in Flint; 6,000-12,000 children exposed; 10,059 pipes replaced by July 2021)](https://en.wikipedia.org/wiki/Flint_water_crisis), Wikipedia (citing EPA, Michigan DEQ, and peer-reviewed epidemiological studies)
46. [Wikipedia — "Infrastructure Investment and Jobs Act" ($55B water provisions; $15B for lead service line replacement; $3B allocated by May 2024)](https://en.wikipedia.org/wiki/Infrastructure_Investment_and_Jobs_Act), Wikipedia (citing White House, EPA, and CBO sources)
47. [Wikipedia — "Lead and Copper Rule" (October 2024 EPA final rule; 10-year replacement deadline; $1.5-2B annual cost; $13-25B annual benefit)](https://en.wikipedia.org/wiki/Lead_and_Copper_Rule), Wikipedia (citing EPA regulatory text and Federal Register)

### Predecessors & successors

48. [United Association — "About the UA" (1889 founding incorporated plumbers, gas fitters, and steam fitters)](https://ua.org/about-the-ua/), United Association
49. [US Navy Seabee Museum — "Seabee History: Construction and Utility Trades in WWII" (pipe-fitting and mechanical trades training)](https://www.history.navy.mil/content/history/museums/seabee.html), US Navy

### Present-day analysis

- [BLS Occupational Outlook Handbook -- Plumbers, Pipefitters, and Steamfitters (2024-34)](https://www.bls.gov/ooh/construction-and-extraction/plumbers-pipefitters-and-steamfitters.htm), accessed 2026-06-03
- [BLS OEWS May 2024 -- 47-2152 Plumbers, Pipefitters, and Steamfitters (national flat file)](https://www.bls.gov/oes/special-requests/oesm24nat.zip), accessed 2026-10-07
- [O\*NET 30.3 -- Plumbers, Pipefitters, and Steamfitters (47-2152.00)](https://www.onetonline.org/link/summary/47-2152.00), accessed 2026-06-03
- [Eloundou et al. 2024 -- GPTs are GPTs (Science)](https://arxiv.org/abs/2303.10130), accessed 2026-06-03
- [SewerAI -- AutoCode AI pipe inspection coding product page](https://www.sewerai.com/products/autocode), accessed 2026-06-03
- [WinCan AI -- Automated sewer defect coding product page](https://www.wincan.com/product/wincan-ai/), accessed 2026-06-03
- [ServiceTitan -- AI for Plumbing Businesses (Atlas AI, Dispatch Pro, Pricebook Pro)](https://www.servicetitan.com/blog/plumbing-ai-tools-for-business), accessed 2026-06-03
- [ServiceTitan -- Atlas AI pushes into commercial construction (ENR, 2025)](https://www.enr.com/articles/61387-servicetitan-pushes-into-commercial-construction-tech-with-atlas-ai), accessed 2026-06-03
- [Electro Scan Inc. -- AI breakthrough for locating leaks in drinking water pipes (2025)](https://www.electroscan.com/electro-scan-inc-announces-artificial-intelligence-ai-breakthrough-for-locating-leaks-in-drinking-water-pipes/), accessed 2026-06-03
- [Trimble MEP -- SysQue pipe modeling for Autodesk Revit](https://www.trimble.com/en/industries/construction/mep), accessed 2026-06-03
- [Plumber Magazine -- Harnessing AI for Pipeline Inspection Productivity (Oct 2025)](https://www.plumbermag.com/online_exclusives/2025/10/harnessing-the-power-of-ai-for-pipeline-inspection-productivity), accessed 2026-06-03
- [PHCP Pros -- AI will not replace plumbers but may help you hire one](https://www.phcppros.com/articles/22550-ai-wont-replace-plumbers-but-it-might-help-you-hire-one), accessed 2026-06-03
- [ServiceTitan -- Dispatch Pro: AI-optimized dispatching for trade contractors](https://www.servicetitan.com/industries/plumbing-software), accessed 2026-06-03
- [ServiceTitan -- Pricebook Pro with Smart Start and Price Insights](https://www.servicetitan.com/features/pro/pricebook), accessed 2026-06-03

How to read these figures: https://futurehistory.earth/methodology. Every figure links to its own source; gaps stay gaps.