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Desalination Recovery Rate Estimator

The Desalination Recovery Rate Estimator calculates the percentage of feed water converted into desalinated product water and shows the corresponding concentrate volume and concentrate fraction. It provides a direct water-balance check for a desalination train or plant boundary using feed and product volumes measured over the same period.

Recovery strongly influences desalination flow requirements, concentrate quantity, and often energy and scaling conditions, so tracking it consistently is useful for both planning and operations. The calculator does not judge whether a particular recovery is appropriate for a feed source or technology; allowable and economical recovery depends on salinity, temperature, pretreatment, membrane or thermal design, scaling limits, concentrate management, and equipment specifications.

Desalination recovery

gal
gal
Result
—
Desalination recovery rate
Concentrate volume—
Concentrate fraction—
Feed-to-product ratio—

1. Enter total feed water
Use the desalination feed volume entering the selected system boundary.

2. Enter product water
Use the desalinated product volume produced over the same period.

3. Match period and boundary
Keep both measurements on the same time basis and avoid counting internal recycle as fresh external feed.

4. Read recovery percentage
The main result shows product water as a percentage of feed water.

5. Review concentrate balance
Use concentrate volume and fraction to understand the feed portion not converted to product in this simple balance.

Recovery rate (%) = Product water ÷ Feed water × 100

Where:

  • Product water: desalinated finished-water output volume
  • Feed water: incoming source-water volume over the same period
  • Concentrate volume: feed water minus product water
  • Concentrate fraction: concentrate volume ÷ feed water × 100

Assumption: The calculator uses a simple volumetric balance and does not account for small chemical-addition volumes, sampling losses, measurement uncertainty, or internal recycle unless included consistently in the chosen boundary.

What the result means

The main result is a planning estimate derived directly from the entered operating assumptions and should be interpreted within the stated system boundary.

Use project-specific design criteria, equipment data, and applicable requirements before making final engineering or procurement decisions.

Given:

  • Feed water = 1,000,000 gal
  • Product water = 450,000 gal

Calculation:
Recovery = 450,000 ÷ 1,000,000 × 100 = 45.00%.
Concentrate = 1,000,000 − 450,000 = 550,000 gal.
Concentrate fraction = 550,000 ÷ 1,000,000 × 100 = 55.00%.

Result:
45.00% desalination recovery.

The simple balance indicates 550,000 gallons, or 55% of feed, on the concentrate side for the measured period.

Is a higher desalination recovery always better?

No. Higher recovery reduces concentrate volume for a given feed but can increase salinity, scaling pressure, energy demands, or process constraints. Appropriate recovery is technology- and feed-specific.

What volumes should be used for a reverse-osmosis train?

Use feed entering the selected train boundary and permeate product leaving it over the same period. Be consistent about whether recycle streams are inside or outside that boundary.

Why can measurement error affect recovery?

Recovery is a ratio of two measured volumes, so meter bias, timing mismatch, or unaccounted side flows can shift the result. Large discrepancies should prompt a water-balance check.

How is concentrate fraction related to recovery?

In this simple two-stream balance, concentrate fraction equals 100% minus recovery. Additional side streams would require a more detailed balance.

How can recovery be used with the flow estimator?

Use the measured or design recovery as an input to the desalination flow-requirements estimator to translate a product target into required feed flow.