Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Numerator:
Numerator for basic and diluted earnings per common share—Net income attributable to Evoqua Water Technologies Corp.	$ 10,632	$ 7,330	$ 19,900	$ 13,317
Denominator:
Denominator for basic net income per common share—weighted average shares	122,212,000	120,942,000	122,028,000	120,785,000
Effect of dilutive securities:
Share‑based compensation	3,583,000	4,012,000	3,479,000	4,145,000
Denominator for diluted net income per common share—adjusted weighted average shares	125,795,000	124,954,000	125,507,000	124,930,000
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
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)	272,000	606,000	493,000	465,000