Share-Based Compensation (Details) - USD ($) $ / shares in Units, shares in Thousands					3 Months Ended
	Oct. 01, 2020	Nov. 02, 2019	Dec. 21, 2018	Nov. 02, 2017	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2020	Feb. 18, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value, exercises in period					$ 19,362,000
Employee Stock Ownership Plan (ESOP), Shares in ESOP			11,297
Common Stock, Par or Stated Value Per Share					$ 0.01		$ 0.01
Non-cash share-based compensation					$ 3,019,000	$ 3,680,000
Share-based Compensation expense					3,076,000	3,691,000
Compensation cost not yet recognized, period for recognition					11,736,000
Fair value of options vested					57,000
Proceeds from issuance of common stock					$ 14,263,000	4,046,000
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plan, number of shares authorized (shares)					5,100			5,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant					5,916
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plan, number of shares authorized (shares)					11,083
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant					2,149
Compensation cost not yet recognized, period for recognition					$ 7,653,000
Period for recognition for unrecognized compensation expense					2 years 1 month 6 days
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period for recognition for unrecognized compensation expense					2 years 2 months 12 days
Aggregate value				$ 25,000
Vested in period (shares)		1,158		1,197	1
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Ownership Plan (ESOP), Shares in ESOP			5,000
Common Stock, Par or Stated Value Per Share			$ 0.01
Employee Stock Ownership Plan (ESOP), Compensation Expense					$ 216,000	$ 39,000
Shares issued under ESPP	120
Evoqua Water Technologies Corp. Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards vesting percentage					25.00%
Treasury Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares withheld related to net share settlement (including tax withholdings) (shares)		419