v3.26.1
Cover Page - shares
6 Months Ended
Jun. 30, 2026
Jul. 31, 2026
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Entity File Number 001-34112  
Entity Registrant Name Energy Recovery, Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 01-0616867  
Entity Address, Address Line One 1717 Doolittle Drive  
Entity Address, City or Town San Leandro  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 94577  
City Area Code 510  
Local Phone Number 483-7370  
Title of 12(b) Security Common Stock, $0.001 par value  
Trading Symbol ERII  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding (in shares)   51,044,875
Entity Central Index Key 0001421517  
Document Fiscal Year Focus 2026  
Current Fiscal Year End Date --12-31  
Document Fiscal Period Focus Q2  
Amendment Flag false