Unaudited Consolidated Statements of Operations - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Revenues [Abstract]
Revenues	$ 477,797,000	$ 426,728,000	$ 913,643,000	$ 792,996,000
Cost of Revenue [Abstract]
Cost of product sales and services	(325,901,000)	(297,842,000)	(631,438,000)	(553,602,000)
Gross profit	151,896,000	128,886,000	282,205,000	239,394,000
Operating Expenses [Abstract]
General and administrative expense	(77,758,000)	(66,976,000)	(141,834,000)	(124,805,000)
Sales and marketing expense	(43,215,000)	(39,859,000)	(83,601,000)	(76,308,000)
Research and development expense	(4,582,000)	(3,751,000)	(8,417,000)	(7,203,000)
Total operating expenses	(125,555,000)	(110,586,000)	(233,852,000)	(208,316,000)
Other operating income	1,827,000	1,415,000	3,124,000	3,072,000
Other operating expense	(4,711,000)	(143,000)	(4,788,000)	(290,000)
Operating profit (loss)	23,457,000	19,572,000	46,689,000	33,860,000
Interest expense	(10,303,000)	(9,950,000)	(20,377,000)	(16,529,000)
Income before income taxes	13,154,000	9,622,000	26,312,000	17,331,000
Income tax expense	(2,522,000)	(2,248,000)	(6,412,000)	(3,869,000)
Net income	10,632,000	7,374,000	19,900,000	13,462,000
Net income attributable to non‑controlling interest	0	44,000	0	145,000
Net income attributable to Evoqua Water Technologies Corp.	$ 10,632,000	$ 7,330,000	$ 19,900,000	$ 13,317,000
Basic income per common share	$ 0.09	$ 0.06	$ 0.16	$ 0.11
Diluted income per common share	$ 0.08	$ 0.06	$ 0.16	$ 0.11
Revenue from product sales
Revenues [Abstract]
Revenues	$ 292,651,000	$ 259,775,000	$ 553,042,000	$ 472,343,000
Cost of Revenue [Abstract]
Cost of product sales and services	(203,101,000)	(185,330,000)	(388,141,000)	(339,125,000)
Revenue from service
Revenues [Abstract]
Revenues	185,146,000	166,953,000	360,601,000	320,653,000
Cost of Revenue [Abstract]
Cost of product sales and services	$ (122,800,000)	$ (112,512,000)	$ (243,297,000)	$ (214,477,000)