Calculator
RO Reject Water Calculator
Estimate RO reject water from permeate flow and recovery percentage.
Calculator Inputs
Legend
RO Reject Water Calculator guidance
Feed flow = permeate flow / recovery fraction. Reject flow = feed flow - permeate flow.
Input meaning
- Permeate flow: enter the measured, quoted, or hospital-approved value in L/min.
- Recovery: enter the measured, quoted, or hospital-approved value in %.
- Operating hours per day: enter the measured, quoted, or hospital-approved value in hours.
Result interpretation
- Use the result as a planning estimate, not as a final approval by itself.
- Record the assumptions used so Procurement, Biomedical, Facilities, Finance, and vendors can review the same basis.
Assumptions
- Reject volume changes with membrane condition, feed water quality, temperature, and system settings.
- Drainage and water-saving plans should be reviewed by facilities and dialysis water specialists.
Biomedical use
- Use this calculator during RFQ preparation, technical evaluation, acceptance planning, service review, or biomedical workload planning.
How to identify the required values
Use these examples and common working ranges to choose values from gauges, labels, manuals, datasheets, RFQs, service reports, CMMS records, or hospital planning assumptions.
| Field | Example value | Common range | Tip |
|---|---|---|---|
| Permeate flow | Example: 10 L/min. | Use stable RO product flow from the flowmeter, not startup or flush flow. | Use stable product-water flow during normal operation. |
| Recovery | Example: 65 %. | Dialysis RO recovery is often around 50-75%, depending on water quality and membrane limits. | Use the RO setpoint or measured recovery during normal production. |
| Operating hours per day | Example: 8 hours. | Intermittent use often 4-12 h/day; continuous ICU/utility use is usually 24 h/day. | Use real operating hours, not department opening hours if equipment remains on. |
Common ranges are starting points for hospital planning. For final procurement, acceptance testing, electrical design, medical gas design, radiation shielding, dialysis water systems, or clinical use, replace the example values with site-specific data and vendor-confirmed figures.
Input Checklist
Confirm these values before relying on the output for procurement, PM, or service planning.
- Permeate flow
- Recovery percentage
- Operating hours
Safety And Engineering Notes
Use calculator outputs as planning estimates and verify critical systems with calibrated measurement or qualified engineering review.
- Reject volume changes with membrane condition, feed water quality, temperature, and system settings.
- Drainage and water-saving plans should be reviewed by facilities and dialysis water specialists.
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