Unaudited Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues [Abstract]
Revenue from product sales and services	$ 347,827	$ 360,343	$ 1,045,595	$ 1,031,973
Cost of Revenue [Abstract]
Cost of product sales and services	(237,593)	(249,049)	(718,440)	(736,338)
Gross profit	110,234	111,294	327,155	295,635
Operating Expenses [Abstract]
General and administrative expense	(44,867)	(49,525)	(152,767)	(152,571)
Sales and marketing expense	(29,855)	(31,959)	(101,845)	(103,546)
Research and development expense	(2,782)	(3,281)	(9,655)	(11,384)
Total operating expenses	(77,504)	(84,765)	(264,267)	(267,501)
Other operating income	621	746	61,859	4,625
Other operating expense	(285)	(184)	(834)	(559)
Operating profit (loss)	33,066	27,091	123,913	32,200
Interest expense	(10,485)	(14,842)	(37,320)	(43,759)
Income (loss) before income taxes	22,581	12,249	86,593	(11,559)
Income tax (expense) benefit	(740)	(7,959)	(3,336)	1,134
Net income (loss)	21,841	4,290	83,257	(10,425)
Net income attributable to non‑controlling interest	457	155	916	786
Net income (loss) attributable to Evoqua Water Technologies Corp.	$ 21,384	$ 4,135	$ 82,341	$ (11,211)
Basic income (loss) per common share	$ 0.18	$ 0.04	$ 0.71	$ (0.10)
Diluted income (loss) per common share	$ 0.18	$ 0.03	$ 0.68	$ (0.10)
Revenue from product sales
Revenues [Abstract]
Revenue from product sales and services	$ 207,575	$ 210,363	$ 610,104	$ 597,319
Cost of Revenue [Abstract]
Cost of product sales and services	(143,457)	(148,417)	(428,069)	(438,869)
Revenue from service
Revenues [Abstract]
Revenue from product sales and services	140,252	149,980	435,491	434,654
Cost of Revenue [Abstract]
Cost of product sales and services	$ (94,136)	$ (100,632)	$ (290,371)	$ (297,469)