Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Revenues [Abstract]
Sales to external customers	$ 1,737,076	$ 1,464,429	$ 1,429,456
Cost of Revenue [Abstract]
Cost of product sales and services	(1,201,097)	(1,007,077)	(979,653)
Gross profit	535,979	457,352	449,803
Operating Expenses [Abstract]
General and administrative expense	(260,550)	(206,455)	(192,597)
Sales and marketing expense	(161,303)	(143,110)	(136,167)
Research and development expense	(15,442)	(13,445)	(13,198)
Total operating expenses	(437,295)	(363,010)	(341,962)
Other operating income	5,726	5,743	61,662
Other operating expense	(417)	(768)	(1,055)
Income before interest expense and income taxes	103,993	99,317	168,448
Interest expense	(34,680)	(37,575)	(46,682)
Income before income taxes	69,313	61,742	121,766
Income tax benefit (expense)	3,030	(10,080)	(7,371)
Net income	72,343	51,662	114,395
Net income attributable to non‑controlling interest	145	180	746
Net income attributable to Evoqua Water Technologies Corp.	$ 72,198	$ 51,482	$ 113,649
Basic income per common share	$ 0.60	$ 0.43	$ 0.97
Diluted income per common share	$ 0.58	$ 0.42	$ 0.94
Product
Revenues [Abstract]
Sales to external customers	$ 1,052,488	$ 861,026	$ 839,857
Cost of Revenue [Abstract]
Cost of product sales and services	(740,464)	(607,693)	(588,264)
Revenue from service
Revenues [Abstract]
Sales to external customers	684,588	603,403	589,599
Cost of Revenue [Abstract]
Cost of product sales and services	$ (460,633)	$ (399,384)	$ (391,389)