Description of the Company and Basis of Presentation	12 Months Ended
Description of the Company and Basis of Presentation	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Company and Basis of Presentation	Description of the Company and Basis of Presentation Background Evoqua Water Technologies Corp. (referred to herein as the “Company” or “EWT”) was incorporated on October 7, 2013. On January 15, 2014, Evoqua Water Technologies Corp., acquired through its wholly owned entities, EWT Holdings II Corp. and EWT Holdings III Corp. (a/k/a Evoqua Water Technologies), all of the outstanding shares of Siemens Water Technologies, a group of legal entity businesses formerly owned by Siemens AG (“Siemens”). The stock purchase closed on January 15, 2014 and was effective January 16, 2014 (the “Acquisition”). The stock purchase price, net of cash received, was approximately $730,577. On November 6, 2017, the Company completed its initial public offering (“IPO”), pursuant to which an aggregate of 27,777 shares of common stock were sold, of which 8,333 were sold by the Company and 19,444 were sold by the selling shareholders, with a par value of $0.01 per share. After underwriting discounts and commissions and other expenses, the Company received net proceeds from the IPO of approximately $137,605. The Company used a portion of these proceeds to repay $104,936 of indebtedness (including accrued and unpaid interest) under EWT III’s senior secured first lien term loan facility and the remainder for general corporate purposes. The Company did not receive any proceeds from the sale of shares by the selling shareholders. On November 7, 2017, the selling shareholders sold an additional 4,167 shares of common stock as a result of the exercise in full by the underwriters of an option to purchase additional shares. On March 19, 2018, the Company completed a secondary public offering, pursuant to which 17,500 shares of common stock were sold by certain selling shareholders. On March 21, 2018, the selling shareholders sold an additional 2,625 shares of common stock as a result of the exercise in full by the underwriters of an option to purchase additional shares. On March 10, 2020 and August 10, 2020, the Company completed additional secondary public offerings, pursuant to which 13,000 and 9,200 shares of common stock were sold by certain selling shareholders, respectively. The Company did not receive any proceeds from the sale of shares by the selling shareholders in any of these secondary public offerings. The Business EWT provides a wide range of product brands and advanced water and wastewater treatment systems and technologies, as well as mobile and emergency water supply solutions and service contract options through its branch network. Headquartered in Pittsburgh, Pennsylvania, EWT is a multi‑national corporation with operations in the United States (“U.S.”), Canada, the United Kingdom (“UK”), the Netherlands, Germany, Australia, the People’s Republic of China, Singapore, the Republic of Korea and India. The Company is organizationally structured into two reportable operating segments for the purpose of making operational decisions and assessing financial performance: (i) Integrated Solutions and Services and (ii) Applied Product Technologies. Basis of Presentation The accompanying Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the U.S. (“GAAP”) from the accounting records of the Company, and reflect the consolidated financial position and results of operations for the fiscal years ended September 30, 2020, 2019 and 2018. Unless otherwise specified, references in this section to a year refer to its fiscal year. All intercompany transactions have been eliminated. Unless otherwise specified, all dollar amounts in this section are referred to in thousands. Certain prior period amounts have been reclassified to conform to the current period presentation.