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Greywater Reuse Recovery Rate Estimator

This estimator calculates the recovery rate of a greywater reuse system by comparing collected source water with the treated water that remains usable after screening, treatment, reject streams, flushing, and other losses. It provides a compact volume-balance metric for tracking system performance over a storm-independent operating period. The tool is useful for commissioning, operations reviews, and comparing treatment configurations when meter data are available. It reports recovered volume, unrecovered volume, and loss rate alongside the main percentage. Use the same measurement period and units for both inputs. Recovery rate should be interpreted together with water quality, system availability, and end-use demand; maximizing volume recovery alone is not a complete measure of system effectiveness.

Inputs

L
L
Result
—
Greywater recovery rate
Recovered usable water—
Unrecovered volume—
Loss rate—

1. Enter collected greywater
Use the volume entering the defined reuse-system boundary during the measurement period.

2. Enter usable treated volume
Use the volume available for approved reuse after treatment and internal losses.

3. Keep units identical
The ratio works with any volume unit as long as both entries use the same one.

4. Align meter periods
Compare values from the same day, month, billing cycle, or other operating period.

5. Review recovery and loss rate
Investigate changes by checking reject, backwash, bypass, leakage, and meter consistency.

Recovery rate (%) = Usable treated volume ÷ Collected greywater × 100 Unrecovered volume = Collected greywater − Usable treated volume Loss rate (%) = 100 − Recovery rate

The calculation assumes the recovered volume is a subset of the collected volume within the same system boundary and period.

What the result means

The recovery rate shows what share of collected greywater remains available as usable treated water.

A lower rate can reflect necessary treatment reject or flushing as well as avoidable losses, so interpret the metric using the process configuration and operating records.

Given
Collected greywater = 12,500 L; usable treated volume = 10,800 L.

Calculation
Recovery rate = 10,800 ÷ 12,500 × 100 = 86.4%.
Unrecovered volume = 12,500 − 10,800 = 1,700 L.
Loss rate = 13.6%.

Result
86.4%

The system returns 86.4% of collected greywater as usable treated water within the defined measurement boundary.

What losses reduce greywater recovery rate?

Depending on the process, losses can include screening waste, filter backwash, membrane reject, tank cleaning, overflow, bypass, leaks, or water held in equipment at the measurement cutoff.

Can recovered volume be higher than collected volume?

Not within a consistent single-source balance. If it appears higher, verify meter calibration, timing, units, stored water carried over from a previous period, or other water entering the system.

Is a higher recovery rate always better?

Not by itself. Some treatment processes intentionally reject water to maintain quality or reliability, so recovery should be considered with treatment performance and operating goals.

How often should recovery be calculated?

Use a period that matches available meter data and operating decisions. Consistent weekly or monthly calculations can be more useful for trend tracking than isolated values.

How is recovery rate different from water savings?

Recovery rate measures process yield from collected greywater. Water savings measures how much conventional supply is displaced by actual reuse demand.