Unaudited Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Revenues [Abstract]
Revenues	$ 426,728	$ 346,564	$ 792,996	$ 668,757
Cost of Revenue [Abstract]
Cost of product sales and services	(297,842)	(240,645)	(553,602)	(467,493)
Gross profit	128,886	105,919	239,394	201,264
Operating Expenses [Abstract]
General and administrative expense	(66,976)	(52,928)	(124,805)	(95,211)
Sales and marketing expense	(39,859)	(33,830)	(76,308)	(67,758)
Research and development expense	(3,751)	(3,393)	(7,203)	(6,516)
Total operating expenses	(110,586)	(90,151)	(208,316)	(169,485)
Other operating income	1,415	511	3,072	991
Other operating expense	(143)	(101)	(290)	(358)
Operating profit (loss)	19,572	16,178	33,860	32,412
Interest expense	(9,950)	(8,395)	(16,529)	(17,068)
Income before income taxes	9,622	7,783	17,331	15,344
Income tax expense	(2,248)	(2,701)	(3,869)	(3,785)
Net income	7,374	5,082	13,462	11,559
Net income attributable to non‑controlling interest	44	46
Net income attributable to Evoqua Water Technologies Corp.	$ 7,330	$ 5,036	$ 13,317	$ 11,469
Basic income per common share	$ 0.06	$ 0.04	$ 0.11	$ 0.10
Diluted income per common share	$ 0.06	$ 0.04	$ 0.11	$ 0.09
Non-controlling Interest
Operating Expenses [Abstract]
Net income	$ 44	$ 46
Net income attributable to non‑controlling interest			$ 145	$ 90
Revenue from product sales
Revenues [Abstract]
Revenues	259,775	202,466	472,343	382,481
Cost of Revenue [Abstract]
Cost of product sales and services	(185,330)	(144,521)	(339,125)	(275,582)
Revenue from service
Revenues [Abstract]
Revenues	166,953	144,098	320,653	286,276
Cost of Revenue [Abstract]
Cost of product sales and services	$ (112,512)	$ (96,124)	$ (214,477)	$ (191,911)