Unaudited Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues [Abstract]
Revenue from product sales and services	$ 342,475	$ 311,142	$ 973,215	$ 890,916
Cost of Revenue [Abstract]
Cost of product sales and services	(240,468)	(210,715)	(674,832)	(614,088)
Gross profit	102,007	100,427	298,383	276,828
Operating Expenses [Abstract]
General and administrative expense	(56,961)	(31,136)	(140,767)	(120,534)
Sales and marketing expense	(33,888)	(36,946)	(102,459)	(108,729)
Research and development expense	(3,682)	(5,592)	(12,356)	(15,684)
Total operating expenses	(94,531)	(73,674)	(255,582)	(244,947)
Other operating (expense) income	7,362	(329)	7,674	981
Interest expense	(12,370)	(12,466)	(40,423)	(39,117)
Income (loss) before income taxes	2,468	13,958	10,052	(6,255)
Income tax (expense) benefit	(1,433)	(12,202)	960	(295)
Net income (loss)	1,035	1,756	11,012	(6,550)
Net income attributable to non‑controlling interest	242	253	1,427	2,348
Net income (loss) attributable to Evoqua Water Technologies Corp.	$ 793	$ 1,503	$ 9,585	$ (8,898)
Basic (loss) earnings per common share (in dollars per share)	$ 0.01	$ 0.01	$ 0.08	$ (0.08)
Diluted (loss) earnings per common share (in dollars per share)	$ 0.01	$ 0.01	$ 0.08	$ (0.08)