Water & Utilities
RO Recovery & Salt Rejection Calculator
Calculate reverse-osmosis recovery, concentrate flow, salt rejection and an optional concentration mass balance.
This tool provides a preliminary engineering calculation for reference. Final equipment selection, design and commissioning decisions must consider manufacturer data, applicable standards, operating conditions and project-specific engineering requirements. It is not certified design output.
Preliminary result
Calculated outputs
Enter values and select Calculate. Results are estimates and do not replace nameplate data, applicable standards, or an engineering review.
Use this calculation
Only calculator parameters and results are transferred. Personal details are collected separately in the destination form.
Formula
Recovery = Qp/Qf × 100
Qc = Qf − Qp
Rejection = (1 − Cp/Cf) × 100
Cc = (QfCf − QpCp)/Qc
Worked example
10 m³/h feed, 7 m³/h permeate, 1000 mg/L feed and 50 mg/L permeate.
Expected check: Recovery = 70; Salt rejection = 95; Concentrate flow = 3.
Assumptions
- • Feed and permeate concentration use the same measurement basis
- • Steady-state overall mass balance
Limitations
- • Does not establish safe membrane recovery or system design
- • Conductivity and TDS are not interchanged automatically
Frequently asked questions
Can this result be used for final equipment selection?
No. Use it for a preliminary check, then verify manufacturer data, site conditions, applicable standards and the complete system design.
What does formula version 1.0.0 mean?
It identifies the exact calculation logic used so a saved result can be traced when the formula register changes.
Can Elexorn review my calculation?
Yes. Transfer the result to Request a Quote or Talk to an Elexorn Engineer and add the relevant project or equipment details.