What is the largest wastewater treatment plant in Tennessee?

Metro Central Wastewater Treatment Plant in Nashville, treating an average of 88.2 MGD under NPDES permit TNL020575. Moccasin Bend Wastewater Treatment Plant in Chattanooga is second at 36.67 MGD.

How much wastewater do Tennessee’s largest plants treat?

The 50 largest plants treat 293 MGD combined, 91% of the flow reported by all 227 publicly owned plants in Tennessee.

How is plant size measured?

By reported average daily flow in million gallons per day (MGD) from EPA discharge monitoring reports, the standard measure of a plant’s size. Design capacity, the flow a plant is permitted to treat, is usually higher and is shown on each profile.

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The 50 largest wastewater treatment plants in Tennessee

Name: Largest wastewater treatment plants in Tennessee
Creator: Klarifi
License: https://klarifi.io/terms-of-service

Ranked by average flow · 293 MGD combined · 91% of the state's reported flow

Metro Central Wastewater Treatment Plant in Nashville is the largest publicly owned wastewater treatment plant in Tennessee by reported average flow, treating about 88.2 million gallons per day. The 50 plants below treat 293 MGD between them, 91% of the flow reported by all 227 plants in the state, and serve about 2,229,362 people. Every plant links to its profile with permit, technology and compliance data.

All plants in Tennessee →The 100 largest US plants →Tennessee NPDES permits →

The 50 largest publicly owned wastewater treatment plants in Tennessee by average flow (MGD), with population served, NPDES permit, expiry, treatment technology and three-year violation count.
#	Facility	City	Avg flow (MGD)	Population	NPDES permit	Expires	Technology	Violations (3y)
1	Metro Central Wastewater Treatment Plant	Nashville	88.2	649,235	TNL020575	Dec 2030	Clarifiers	62
2	Moccasin Bend Wastewater Treatment Plant	Chattanooga	36.67	262,562	TNR053775	Jun 2030	Clarifiers, Aerated lagoons, Uncovered lagoons, Biogas silos	53
3	Whites Creek Wastewater Treatment Plant	Nashville	21.51	54,671	TN0024970	Oct 2025	Clarifiers, Aerated lagoons, Biogas balloons	39
4	Nashville Dry Creek STP	Madison	12.69	201,478	TN0020648	Oct 2025	Clarifiers, Biogas silos, Biogas balloons	34
5	City Of Cookeville Department Of Water Quality Control (wwtp)	Cookeville	9.62	38,338	TN0024198	Jun 2027	Clarifiers, Uncovered lagoons, Carrousels / oxidation ditches	27
6	Kingsport STP	Kingsport	8.68	55,093	TN0020095	Dec 2028	Clarifiers, Biogas silos, Biogas balloons	36
7	City Of Franklin Wastewater Treatment Plant	Franklin	7.12	80,675	TN0028827	Dec 2026	Clarifiers, Carrousels / oxidation ditches, Biogas silos	44
8	Cleveland Utilities Wastewater Treatment Plant	Charleston	6.59	65,814	TN0024121	Apr 2027	Clarifiers, Aerated lagoons	43
9	Johnson City STP	Johnson City	5.49	66,934	TN0024244	Sep 2026	Clarifiers	23
10	Sevierville (mccroskey Island) STP	Sevierville	5.32	17,185	TN0063959	Apr 2030	Clarifiers, Uncovered lagoons, Carrousels / oxidation ditches	115
11	City Of Columbia Wastewater Treatment Plant	Columbia	5.06	39,515	TN0056103	Oct 2028	Clarifiers	68
12	Turkey Creek WWTP (morristown Stp)	Morristown	4.87	38,163	TN0023507	Oct 2029	Clarifiers, Biogas silos	22
13	Harpeth Valley Utility District STP	Nashville	4.76	27,220	TN0074748	Feb 2030	Clarifiers, Carrousels / oxidation ditches	4
14	Hallsdale-Powell U.D.-Melton Hill Lk	Knoxville	4.48	81,175	TN0078905	Sep 2028	Clarifiers, Aerated lagoons, Carrousels / oxidation ditches	44
15	Oak Ridge STP	Oak Ridge	4.1	29,124	TN0024155	Dec 2028	Clarifiers	35
16	West Knox Ud Melton Lake WWTP	Knoxville	3.94	55,529	TN0080721	Mar 2028	—	13
17	City Of Spring Hill STP	Spring Hill	3.65	41,797	TN0075868	Dec 2028	Clarifiers, Carrousels / oxidation ditches	42
18	Collierville Northwest STP	Collierville	3.38	25,298	TN0078841	Jan 2028	Clarifiers, Carrousels / oxidation ditches, Biogas balloons	3
19	Denzil Bowman Wastewater Treatment Plant (greeneville Stp)	Greeneville	3.34	14,938	TN0021229	Oct 2030	Clarifiers, Carrousels / oxidation ditches	28
20	Dyersburg STP	Dyersburg	3.12	18,727	TN0023477	Dec 2027	Clarifiers, Aerated lagoons	20
21	Knob Creek Waste Water Plant	Johnson City	3.07	14,154	TN0024236	Sep 2026	Carrousels / oxidation ditches	17
22	Humboldt Utilities Authority	Humboldt	3.04	8,145	TN0062588	Aug 2027	Aerated lagoons	7
23	Shelbyville Wastewater Treatment Plant	Shelbyville	3.04	21,841	TN0024180	Jan 2029	Clarifiers, Carrousels / oxidation ditches	22
24	Crossville STP	Crossville	2.61	14,372	TN0024996	Dec 2026	Clarifiers, Carrousels / oxidation ditches	26
25	Jackson Energy Auth- Middle Fk	Jackson	2.45	26,036	TN0075876	May 2027	—	6
26	Gatlinburg STP	Gatlinburg	2.24	3,944	TN0020117	Aug 2030	Clarifiers, Biogas silos, Biogas balloons	17
27	Union City STP Aka A.L. Strub Wastewater Treatment Plant	Union City	2.2	10,952	TN0021580	Oct 2030	—	1
28	Tullahoma STP	Tullahoma	2.2	19,982	TN0023469	Jul 2027	Aerated lagoons	6
29	Manchester STP	Manchester	2.15	10,896	TN0025038	Feb 2029	Clarifiers, Carrousels / oxidation ditches	40
30	Lewisburg STP	Lewisburg	2.1	12,150	TN0022888	May 2028	Clarifiers, Biogas silos	24
31	Dickson STP	Dickson	2	20,986	TN0066958	Dec 2026	Clarifiers, Carrousels / oxidation ditches	21
32	Elizabethton WWTP	Elizabethton	1.8	13,568	TN0023515	Aug 2031	Clarifiers, Aerated lagoons, Carrousels / oxidation ditches	18
33	Clinton WWTP #1	Clinton	1.72	11,062	TN0026506	May 2028	Clarifiers, Biogas silos	0
34	Newport Utilities Board Wastewater Treatment Plant	Newport	1.56	6,865	TN0020702	Mar 2030	Clarifiers, Uncovered lagoons	9
35	Smithville STP	Smithville	1.47	4,781	TN0065358	Sep 2027	Uncovered lagoons	1
36	Lenoir City STP	Lenoir City	1.43	17,047	TN0020494	Jul 2031	Clarifiers, Uncovered lagoons, Carrousels / oxidation ditches, Biogas silos	11
37	City Of Pulaski Wastewater Treatment Plant	Pulaski	1.4	7,614	TN0021687	Oct 2027	Clarifiers, Uncovered lagoons	2
38	Arlington STP	Arlington	1.27	11,715	TN0078603	Nov 2027	Aerated lagoons	99
39	Martin STP	Martin	1.21	10,585	TN0062545	May 2030	Clarifiers, Uncovered lagoons, Carrousels / oxidation ditches	20
40	Mcminnville Wastewater Plant	Mcminnville	1.21	13,695	TN0023591	Jan 2028	Clarifiers, Carrousels / oxidation ditches	4
41	Town Of Collierville	Collierville	1.16	25,298	TN0057461	Dec 2028	Clarifiers, Carrousels / oxidation ditches	5
42	Lexington Utilities- Waste Water Treatment Plant	Lexington	1.13	7,838	TN0024341	Oct 2028	Clarifiers, Aerated lagoons	6
43	Munford Sewer Department Lagoon	Munford	1.04	18,918	TN0062499	Dec 2030	Aerated lagoons	10
44	Covington Wastewater Treatment Plant	Covington	1.01	8,863	TN0020982	Mar 2029	Clarifiers, Carrousels / oxidation ditches	1
45	Selmer STP	Selmer	1	5,328	TN0062308	Dec 2029	Uncovered lagoons	118
46	Milan STP	Milan	0.97	7,642	TN0062375	Jul 2030	Clarifiers	43
47	Sweetwater STP	Sweetwater	0.92	5,894	TN0020052	Mar 2031	Clarifiers	9
48	City Of Rogersville	Rogersville	0.9	4,412	TN0020672	Dec 2029	Clarifiers	17
49	Jefferson City STP	Jefferson City	0.88	8,220	TN0021199	Dec 2029	Clarifiers, Uncovered lagoons	5
50	City Of Portland 2021 Gravity Sewer Interceptor	Portland	0.87	13,088	TN0021865	Aug 2029	—	231

Largest plants in Tennessee: questions

Sources and methodology

Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.

Data refreshed September 11, 2026.

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