Wastewater Treatment Plants in the US

Introduction

The United States operates somewhere in the region of 16,000 publicly owned wastewater treatment facilities, collectively serving roughly three quarters of the population. The vast majority are small, treating under one million gallons per day and serving communities of a few thousand people. A very small number are enormous, and those few handle a disproportionate share of the national total. Understanding that distribution is the starting point for understanding how wastewater is managed in this country.

The largest facilities cluster where population does: the New York metropolitan area, greater Los Angeles, Chicago, the Bay Area, and the older industrial cities of the Northeast and Midwest. Several of them are among the largest treatment plants in the world. They are also, in many cases, the oldest, having been built or substantially expanded during the federal construction grants era of the 1970s and 1980s, which is why so many are now working through major rehabilitation programs simultaneously.

This article lists the fifty largest US wastewater treatment plants by population served and provides the context needed to interpret that ranking. It sits within the broader water supply picture, since the capacity described here represents the return half of the urban water cycle.

How to Read This Ranking

Rankings of treatment plants are less straightforward than they appear, and three caveats apply to any list of this kind.

Population served and design capacity are different measures. A plant serving a dense residential area may treat less flow than one serving a smaller population with heavy industrial contribution. Ranking by population produces a different order than ranking by million gallons per day, and published figures for the same facility frequently disagree because one source cites permitted flow and another cites average daily flow.

Service area boundaries are not always clean. Regional authorities treat flow from multiple municipalities, and some plants accept trucked or conveyed waste from well outside their nominal service area. New York City’s system illustrates the complication well: fourteen facilities serve one city, so the individual plant populations are large but the city total is divided among them.

Operating authority changes. Detroit’s treatment plant transferred from the city department to the Great Lakes Water Authority in 2016, and similar regionalizations have occurred elsewhere. Older sources may name an operator that no longer runs the facility.

The Fifty Largest US Wastewater Treatment Plants

Ranked by population served:

1. Hyperion Treatment Plant (Los Angeles, CA)
2. Deer Island Sewage Treatment Plant (Boston, MA)
3. Stickney Water Reclamation Plant (Chicago, IL)
4. Blue Plains Advanced Wastewater Treatment Plant (Washington, D.C.)
5. Newtown Creek Wastewater Treatment Plant (New York, NY)
6. North Regional Wastewater Treatment Plant (Miami, FL)
7. Point Loma Wastewater Treatment Plant (San Diego, CA)
8. 26th Ward Wastewater Treatment Plant (New York, NY)
9. Hunts Point Wastewater Treatment Plant (New York, NY)
10. Wards Island Wastewater Treatment Plant (New York, NY)
11. Donald C. Tillman Water Reclamation Plant (Los Angeles, CA)
12. Bowery Bay Wastewater Treatment Plant (New York, NY)
13. Southerly Wastewater Treatment Plant (Cleveland, OH)
14. Trinity River Authority Central Regional Wastewater System (Dallas, TX)
15. Joint Water Pollution Control Plant (Carson, CA)
16. Passaic Valley Sewerage Commission (Newark, NJ)
17. City of Philadelphia Water Department, Northeast Water Pollution Control Plant (Philadelphia, PA)
18. Orange County Sanitation District, Plant No. 1 (Fountain Valley, CA)
19. City of Detroit Water and Sewerage Department, Wastewater Treatment Plant (Detroit, MI)
20. East Bay Municipal Utility District, Main Wastewater Treatment Plant (Oakland, CA)
21. San Jose-Santa Clara Regional Wastewater Facility (San Jose, CA)
22. Sacramento Regional Wastewater Treatment Plant (Elk Grove, CA)
23. Almeda Sims Regional Wastewater Treatment Plant (Houston, TX)
24. North Side Water Reclamation Plant (Skokie, IL)
25. 69th Street Wastewater Treatment Plant (Upper Darby, PA)
26. Central District Wastewater Treatment Facility (Miami, FL)
27. Western Regional Wastewater Treatment Plant (Boynton Beach, FL)
28. City and County of Honolulu, Sand Island Wastewater Treatment Plant (Honolulu, HI)
29. Robert W. Hite Treatment Facility (Denver, CO)
30. Mill Creek Wastewater Treatment Plant (Cincinnati, OH)
31. South District Wastewater Treatment Plant (Miami, FL)
32. Calumet Water Reclamation Plant (Chicago, IL)
33. North Regional Wastewater Treatment Plant (Broward County, FL)
34. Allegheny County Sanitary Authority, Wastewater Treatment Plant (Pittsburgh, PA)
35. East Water Purification Plant (Houston, TX)
36. North Durham Water Reclamation Facility (Durham, NC)
37. Metropolitan Wastewater Treatment Plant (St. Paul, MN)
38. 91st Avenue Wastewater Treatment Plant (Phoenix, AZ)
39. George W. Kuhn Retention Treatment Basin (Oakland County, MI)
40. South Shore Water Reclamation Facility (Milwaukee, WI)
41. Pima County Wastewater Reclamation Facility (Tucson, AZ)
42. McAlpine Creek Wastewater Management Facility (Charlotte, NC)
43. Tres Rios Water Reclamation Facility (Phoenix, AZ)
44. Niagara Falls Wastewater Treatment Plant (Niagara Falls, NY)
45. Upper Occoquan Service Authority Regional Water Reclamation Plant (Centreville, VA)
46. Western Branch Wastewater Treatment Plant (Upper Marlboro, MD)
47. Sod Run Wastewater Treatment Plant (Perryman, MD)
48. Valley Creek Wastewater Treatment Plant (Birmingham, AL)
49. Village Creek Wastewater Treatment Plant (Fort Worth, TX)
50. Papillion Creek Water Resource Recovery Facility (Omaha, NE)

What the Largest Plants Have in Common

Reading down the list, a few patterns emerge that say something useful about American wastewater infrastructure.

Coastal discharge shapes the West Coast plants. Hyperion, Point Loma, the Joint Water Pollution Control Plant, and San Jose-Santa Clara all discharge to the Pacific through ocean outfalls. Ocean discharge permits differ substantially from inland river permits, and Point Loma in particular has operated for decades under a modified permit reflecting that difference.

Combined sewers define the older Eastern and Midwestern plants. Newtown Creek, Stickney, the Philadelphia plants, Allegheny County, and Detroit all serve combined systems where stormwater and sanitary flow share the same pipes. That is why peak wet weather flows at these facilities run several times their design capacity, and why nearly all of them operate under federal consent decrees governing overflow reduction.

The arid Southwest plants are reuse-oriented. The 91st Avenue and Tres Rios facilities in Phoenix, Pima County in Tucson, and the Upper Occoquan plant in Virginia all produce water for beneficial reuse rather than treating discharge as disposal. Upper Occoquan in particular has practiced indirect potable reuse since the late 1970s and is among the longest-running such schemes in the country.

Regional authorities dominate at the top. Many of the largest facilities are operated by regional bodies rather than individual cities: the Metropolitan Water Reclamation District in Chicago, the Massachusetts Water Resources Authority in Boston, the Trinity River Authority in Dallas, the Great Lakes Water Authority in Detroit, and the Passaic Valley Sewerage Commission in New Jersey. Consolidating treatment across municipal boundaries has been the dominant structural trend in American wastewater management for fifty years.

Why the Largest Plants Matter Disproportionately

A handful of facilities treating a large share of national flow has practical consequences. These plants set the technology benchmark, since they are large enough to justify pilot testing and to absorb the cost of a first installation. Thermal hydrolysis, advanced nutrient removal, and biogas-to-renewable-natural-gas conversion all entered American practice at facilities of this scale before becoming viable further down.

They also carry concentrated risk. A failure at a plant serving a million people is a different event from a failure at one serving five thousand, which is why resilience investment, power redundancy, and flood hardening are so heavily weighted toward the top of this list. Several of these facilities sit at low elevation adjacent to the water they discharge into, and post-storm recovery experience at Bay Park in New Jersey and the New York City plants after Superstorm Sandy has driven substantial hardening programs across the sector.

Related Topics

For the count itself and how it is arrived at, coverage of how many wastewater treatment plants in the US addresses the national inventory, the sources that track it, and why published figures vary depending on what is being counted. This article covers the largest facilities; that one covers the population of facilities as a whole.

The institutional side is covered under municipal wastewater management, which addresses the strategies, governance structures, and funding mechanisms through which these plants are planned, financed, and operated. And for the questions the public most often asks about facilities of this size, community impact of wastewater plants covers odor, health risk, property effects, and the siting concerns that accompany any large treatment facility.

Conclusion

The fifty facilities above represent the visible top of a system that is overwhelmingly composed of small plants in small communities. They are where the technology advances first, where the consent decrees concentrate, and where a single failure has the largest consequence. They are also, in most cases, a half-century old and working through the capital renewal that age implies.

For anyone tracking the American wastewater sector, these plants are the useful leading indicator. What Chicago, Los Angeles, and New York adopt this decade tends to become standard practice for mid-size utilities in the next one.