Energy Recovery Inc. (ERII) operates in its industry, providing energy recovery technology for desalination and industrial applications. The company demonstrates exceptional Shariah compliance with minimal debt, no non-permissible income, and a permissible business model focused on sustainable solutions. All major financial ratios are well within thresholds across AAOIFI, MSCI, and S&P standards. Inclusion in all major Shariah indices confirms market acceptance. No purification is required, and ESG factors align strongly with Islamic principles of stewardship and justice.