Unaudited Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Revenues [Abstract]
Revenue from product sales and services	$ 366,268	$ 322,193
Cost of Revenue [Abstract]
Cost of product sales and services	(255,760)	(226,848)
Gross profit	110,508	95,345
Operating Expenses [Abstract]
General and administrative expense	(57,829)	(42,283)
Sales and marketing expense	(36,449)	(33,928)
Research and development expense	(3,452)	(3,123)
Total operating expenses	(97,730)	(79,334)
Other operating income	1,657	480
Other operating expense	(147)	(257)
Operating profit (loss)	14,288	16,234
Interest expense	(6,579)	(8,673)
Income before income taxes	7,709	7,561
Income tax expense	(1,621)	(1,084)
Net income	6,088	6,477
Net income attributable to Evoqua Water Technologies Corp.	$ 5,987	$ 6,433
Basic income per common share	$ 0.05	$ 0.05
Diluted income per common share	$ 0.05	$ 0.05
Non-controlling Interest
Operating Expenses [Abstract]
Net income	$ 101	$ 44
Net income attributable to non‑controlling interest	101	44
Revenue from product sales
Revenues [Abstract]
Revenue from product sales and services	212,568	180,015
Cost of Revenue [Abstract]
Cost of product sales and services	(153,795)	(131,061)
Revenue from service
Revenues [Abstract]
Revenue from product sales and services	153,700	142,178
Cost of Revenue [Abstract]
Cost of product sales and services	$ (101,965)	$ (95,787)