# Water and Wastewater Treatment Plant and System Operators

US SOC code 51-8031. Markdown version of https://futurehistory.earth/timeline/51-8031

Also called: Water treatment operator, Wastewater treatment operator, Plant operator, Water plant operator, WWT operator.

## In brief

In May 2025, [BLS](https://www.bls.gov/oes/special-requests/oesm25nat.zip) counted **128,490** US water and wastewater treatment plant and system operators, with median pay of **$60,020** a year. Of the BLS counts since 2012, the May 2025 count is the highest. The earliest figure here is [an estimate](https://www2.census.gov/library/publications/decennial/1940/population-occupation/00312147ch2.pdf) of **25,000** from 1940, not measured the same way as today's count. The last full technology era in this work: WIMS + advanced metering infrastructure, 2010 to 2022.

## What the sources say

### Official outlook

BLS projects employment to decline 5.7% from 2025 to 2035. Source: [BLS Employment Projections 2025-35](https://data.bls.gov/projections/nationalMatrix?queryParams=51-8031&ioType=o).

### AI exposure studies

- **12.5%** 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)

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.

## Water and Wastewater Treatment Plant and System Operators employment and pay by year

- On record since: 1872
- Latest US employment: 128,490 (May 2025). Source: BLS OEWS May 2025 [4]
- Latest US median pay: $60,020 (May 2025). Source: BLS OEWS May 2025 [9]
- Outlook: -5.7% by 2035. Source: BLS Employment Projections 2025-35 [25]

### 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 92101)
  - Employment, 2020: 13,360. Source: Statistics Canada Census 2021 [7]. Statistics Canada Census of Population 2021: number of persons with employment income in NOC 92101 Water and waste treatment plant operators, Canada, reference year 2020. A recipients basis (anyone with employment income during the year), slightly broader than a point-in-time employed count. Statistics Canada Open Licence.
  - Median pay, 2020: C$75,000. Source: Statistics Canada Census 2021 [12]. Statistics Canada Census of Population 2021 (Table 98-10-0586): median employment income for NOC 92101 Water and waste treatment plant operators, Canada, reference year 2020, full-year full-time workers (the basis comparable to the US OEWS full-time median). Statistics Canada Open Licence.

### All 26 years of cited US data

| Year | US employment | Annual pay (median unless marked) | Source |
| --- | --- | --- | --- |
| 1940 | 25,000 (estimate) | n/a | Est., US Census Bureau [1] |
| 1972 | 40,000 (estimate) | n/a | Est., Wastewater Digest [2] |
| 1996 | 98,000 | $28,652 | BLS CPS 1996 [3] |
| 2003 | 95,870 | $33,910 | BLS OEWS May 2003 [4] |
| 2004 | 92,120 | $34,960 | BLS OEWS May 2004 [4] |
| 2005 | 102,940 | $34,930 | BLS OEWS May 2005 [4] |
| 2006 | 106,550 | $36,070 | BLS OEWS May 2006 [4] |
| 2007 | 108,290 | $37,090 | BLS OEWS May 2007 [4] |
| 2008 | 110,300 | $38,430 | BLS OEWS May 2008 [4] |
| 2009 | 109,090 | $39,850 | BLS OEWS May 2009 [4] |
| 2010 | 108,330 | $40,770 | BLS OEWS May 2010 [4] |
| 2011 | 109,190 | $41,780 | BLS OEWS May 2011 [4] |
| 2012 | 108,440 | $42,760 | BLS OEWS May 2012 [4] |
| 2013 | 110,230 | $43,200 | BLS OEWS May 2013 [4] |
| 2014 | 111,640 | $44,100 | BLS OEWS May 2014 [4] |
| 2015 | 114,770 | $44,790 | BLS OEWS May 2015 [4] |
| 2016 | 115,840 | $45,760 | BLS OEWS May 2016 [4] |
| 2017 | 117,450 | $46,150 | BLS OEWS May 2017 [4] |
| 2018 | 123,650 | $46,780 | BLS OEWS May 2018 [4] |
| 2019 | 123,730 | $47,760 | BLS OEWS May 2019 [4] |
| 2020 | 119,380 | $49,090 | BLS OEWS May 2020 [4] |
| 2021 | 121,150 | $47,880 | BLS OEWS May 2021 [4] |
| 2022 | 119,350 | $51,600 | BLS OEWS May 2022 [4] |
| 2023 | 120,710 | $54,890 | BLS OEWS May 2023 [4] |
| 2024 | 126,750 | $58,260 | BLS OEWS May 2024 [4] |
| 2025 | 128,490 | $60,020 | BLS OEWS May 2025 [4] |

## Sources (88)

### Employment series

1. [US Census Bureau -- Comparative Occupation Statistics for the United States, 1870-1940 (Water and Gas Works Operatives category)](https://www2.census.gov/library/publications/decennial/1940/population-occupation/00312147ch2.pdf), US Census Bureau
2. [Wastewater Digest -- "The Water and Wastewater Workforce" (workforce history, Clean Water Act era)](https://www.wwdmag.com/water/article/10919584/the-water-wastewater-workforce), Wastewater Digest
3. [U.S. Bureau of Labor Statistics, Occupational Outlook Handbook, 1998-99 edition: water and wastewater treatment plant and system operators held about 98,000 jobs in 1996.](https://www.bls.gov/ooh/production/water-and-wastewater-treatment-plant-and-system-operators.htm), U.S. Bureau of Labor Statistics
4. 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)
5. [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
6. [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
7. [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

### Wage series

8. [U.S. Bureau of Labor Statistics, Occupational Outlook Handbook, 1998-99 edition: median weekly earnings of $551 in 1996 (annualized to $28,652), from the Current Population Survey.](https://www.bls.gov/ooh/production/water-and-wastewater-treatment-plant-and-system-operators.htm), U.S. Bureau of Labor Statistics
9. 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)
10. [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
11. [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
12. [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

### Tool eras

13. [Wiki Sanitarc -- "1871: J. P. Kirkwood designed first water filtration plant in the United States at Poughkeepsie, N.Y." (placed into service July 8, 1872)](https://www.wiki.sanitarc.si/1871-j-p-kirkwood-designed-first-water-filtration-plant-united-states-poughkeepsie-n-y/), Wiki Sanitarc (citing primary sanitary engineering history)
14. [Wikipedia -- History of municipal treatment of drinking water (slow-sand filter operations and filter tender role)](https://en.wikipedia.org/wiki/History_of_municipal_treatment_of_drinking_water), Wikipedia
15. [ASDWA -- "History of Chlorination: September 26, 1908 -- First Continuous Use of Chlorine in US Drinking Water"](https://www.asdwa.org/2018/09/26/history-of-chlorination/), Association of State Drinking Water Administrators
16. [Water and Health Council -- "A Public Health Giant Step: Chlorination of U.S. Drinking Water" (typhoid decline 1910-1940)](https://waterandhealth.org/safe-drinking-water/newsletter-may-2008/), Water Quality and Health Council
17. [Wastewater Digest -- History of SCADA for the Water Sector (electromechanical control room era preceding SCADA)](https://www.wwdmag.com/utility-management/article/10940688/a-history-of-scada-for-the-water-sector), Wastewater Digest
18. [EPA -- History of the Clean Water Act (1972 amendments requiring secondary treatment; employment growth driver)](https://www.epa.gov/laws-regulations/history-clean-water-act), US Environmental Protection Agency
19. [Alliance Water Resources -- "Improved Water and Wastewater Systems Monitoring and Automation with SCADA"](https://alliancewater.com/how-does-scada-help-water-and-wastewater-management/), Alliance Water Resources
20. [Hach WIMS -- Water Information Management Solution: automates EPA/state report templates from SCADA data (Aquatic Informatics, 2024)](https://www.hach.com/digital-solutions/wims), Hach / Aquatic Informatics
21. [O\*NET 30.3 -- Water and Wastewater Treatment Plant and System Operators: technology skills include SCADA software and GIS systems](https://www.onetonline.org/link/summary/51-8031.00), O\*NET / BLS
22. [Veolia Water Technologies -- How Digital Twins transform wastewater treatment: -35% electricity, -60% chemical usage at Koege-Egnens (2024)](https://blog.veoliawatertechnologies.com/en/how-digital-twins-transform-wastewater-treatment-with-real-time-optimization), Veolia Water Technologies
23. [Automation.com -- 25% of public-sector wastewater treatment plants to use AI in 2025 (June 2025)](https://www.automation.com/en-us/articles/june-2025/25-percent-public-sector-wwtp-ai-2025), Automation.com
24. [BLS Occupational Outlook Handbook -- Water and Wastewater Treatment Plant and System Operators: automation cited as driver of -7% employment projection 2024-2034](https://www.bls.gov/ooh/production/water-and-wastewater-treatment-plant-and-system-operators.htm), Bureau of Labor Statistics

### Forecasts and exposure studies

25. [BLS Employment Projections 2025-35, National Employment Matrix: 51-8031 Water and wastewater treatment plant and system operators (2025: 131.0 thousand; 2035: 123.5 thousand; -5.7%)](https://data.bls.gov/projections/nationalMatrix?queryParams=51-8031&ioType=o), Bureau of Labor Statistics
26. [Eloundou, Manning, Mishkin & Rock (2023), "GPTs are GPTs", occupation-level exposure data occ\_level.csv (O\*NET-SOC 51-8031.00, human-rated β 0.125)](https://github.com/openai/GPTs-are-GPTs/blob/main/data/occ_level.csv), OpenAI

### Historical notes

27. [Wiki Sanitarc -- "1871: J. P. Kirkwood designed first water filtration plant in the United States at Poughkeepsie, N.Y." (placed into service July 8, 1872)](https://www.wiki.sanitarc.si/1871-j-p-kirkwood-designed-first-water-filtration-plant-united-states-poughkeepsie-n-y/), Wiki Sanitarc
28. [Treatment Plant Operator magazine -- "Bethlehem Waterworks: The Birthplace of U.S. Water Treatment" (includes AWWA founding 1881 history)](https://www.tpomag.com/bytes/2024/12/bethlehem-waterworks-the-birthplace-of-u-s-water-treatment), Treatment Plant Operator
29. [ASDWA -- "History of Chlorination: September 26, 1908" (first continuous chlorination, Jersey City, NJ)](https://www.asdwa.org/2018/09/26/history-of-chlorination/), Association of State Drinking Water Administrators
30. [EPA -- History of the Clean Water Act (1972 amendments requiring secondary treatment, $65B construction grant program)](https://www.epa.gov/laws-regulations/history-clean-water-act), US Environmental Protection Agency
31. [EPA -- About Operator Certification: Safe Drinking Water Act 1996 Amendments, Section 1419, and EPA 1999 guidelines](https://www.epa.gov/dwcapacity/about-operator-certification), US Environmental Protection Agency
32. [National League of Cities -- Building a Resilient Water Workforce in U.S. Cities (Apr 2026): 30%+ age 55+, succession risk](https://www.nlc.org/article/2026/04/20/building-a-resilient-water-workforce-in-u-s-cities/), National League of Cities

### Predecessors & successors

33. [Wiki Sanitarc -- 1872 Poughkeepsie filtration plant (filter tenders and pumping-station attendants as occupation precursors)](https://www.wiki.sanitarc.si/1871-j-p-kirkwood-designed-first-water-filtration-plant-united-states-poughkeepsie-n-y/), Wiki Sanitarc

### Present-day analysis

- [O\*NET 30.3 -- Water and Wastewater Treatment Plant and System Operators (51-8031.00)](https://www.onetonline.org/link/summary/51-8031.00), accessed 2026-06-05
- [BLS Occupational Outlook Handbook -- Water and Wastewater Treatment Plant and System Operators (2024-34 projections: -7% employment, 10,700 annual openings)](https://www.bls.gov/ooh/production/water-and-wastewater-treatment-plant-and-system-operators.htm), accessed 2026-06-05
- [Eloundou et al. 2024 -- GPTs are GPTs: Labor Market Impact Potential of LLMs (Science, vol. 384)](https://arxiv.org/abs/2303.10130), accessed 2026-06-05
- [Automation.com -- 25% of public-sector wastewater treatment plants to use AI in 2025 (June 2025)](https://www.automation.com/en-us/articles/june-2025/25-percent-public-sector-wwtp-ai-2025), accessed 2026-06-05
- [AWWA -- Workforce research: one-third of water sector workforce nearing retirement (2025)](https://www.awwa.org/resource/workforce/), accessed 2026-06-05
- [National League of Cities -- Building a Resilient Water Workforce in U.S. Cities (Apr 2026)](https://www.nlc.org/article/2026/04/20/building-a-resilient-water-workforce-in-u-s-cities/), accessed 2026-06-05
- [Veolia Water Technologies -- How Digital Twins transform wastewater treatment with real-time optimization (Hubgrade, 2024)](https://blog.veoliawatertechnologies.com/en/how-digital-twins-transform-wastewater-treatment-with-real-time-optimization), accessed 2026-06-05
- [Jacobs -- AI and machine learning for wastewater treatment optimization (Intelligent O&M, Palantir Foundry, 2025)](https://www.jacobs.com/insights/thought-leadership/ai-and-machine-learning-wastewater-treatment-optimization), accessed 2026-06-05
- [Veolia AI on SCADA -- AI anticipates problems before they occur, proposes adjustments, operators authorize automated corrections](https://blog.veolianorthamerica.com/how-ai-taking-scada-systems-to-next-level), accessed 2026-06-05
- [ScienceDirect -- AI for smart wastewater treatment plants: physics-informed water quality modeling and advanced control (2026)](https://www.sciencedirect.com/science/article/abs/pii/S0301479726004093), accessed 2026-06-05
- [Hydromantis Mantis.AI -- real-time digital twin for wastewater: forecasts influent loads, monitors plant health, runs scenario simulations (2025)](https://www.hydromantis.com/MantisAI.html), accessed 2026-06-05

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