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Composting Water Savings Estimator

The Composting Water Savings Estimator compares two water-intensity assumptions to estimate the annual water difference associated with a composting operation. It applies the comparison only to the share of annual tonnage that is actually covered by the program, which helps separate total site throughput from the material affected by the change. For composting planning, “baseline” should represent the water use of the displaced or previous handling pathway, while “program” should reflect the water directly assigned to the selected process boundary. The two intensities must be measured on the same gallons-per-ton basis to make the comparison meaningful. A positive result indicates modeled water savings; a negative result indicates that the program uses more water than the chosen baseline under the entered assumptions. The estimate is best used for scenario comparison and screening, not as a substitute for a full life-cycle water inventory.

Water-use comparison inputs

tons/yr
gal/ton
gal/ton
%
Result
—
estimated annual water savings
Applicable throughput—
Baseline water use—
Program water use—

1. Enter annual throughput
Provide the total tons of organic feedstock considered during one year.

2. Define baseline water intensity
Enter gallons per ton for the comparison pathway using a consistent system boundary.

3. Enter program water intensity
Provide gallons per ton attributed to the composting operation under the same boundary.

4. Set the applicable share
Use the percentage of annual throughput for which the baseline-to-program comparison actually applies.

5. Read the annual difference
The main result reports baseline water minus program water. Negative values mean modeled water use increased.

Applicable tons = Annual throughput × Applicable share / 100 Baseline water = Applicable tons × Baseline water intensity Program water = Applicable tons × Program water intensity Water savings = Baseline water − Program water

Throughput is in tons per year and both intensity values are in gallons per ton, producing gallons per year. The estimator does not assign an external water footprint automatically; the user must choose comparable baseline and program boundaries.

What the result means

The result is the annual water-use difference for the portion of throughput included in the comparison. Positive values are savings relative to the selected baseline.

Indirect water use, regional water scarcity, wastewater quality, and upstream supply-chain effects are outside the calculation unless they are already embedded in the entered intensities.

Given: 6,000 tons/year, baseline water intensity 220 gal/ton, program intensity 85 gal/ton, and 90% applicable throughput.

Calculation:
Applicable tons = 6,000 × 0.90 = 5,400 tons/year.
Baseline water = 5,400 × 220 = 1,188,000 gal/year.
Program water = 5,400 × 85 = 459,000 gal/year.
Water savings = 1,188,000 − 459,000 = 729,000 gal/year.

Result: Estimated annual savings are 729,000 gallons.

Interpretation: Under these boundaries, the selected program pathway uses that much less water each year than the chosen baseline for the applicable tonnage.

What should I use as the baseline water intensity?

Use a measured or defensible gallons-per-ton value for the pathway being replaced or compared. Keep the included operations consistent with the program water-intensity estimate.

Why is there an applicable throughput percentage?

Not every ton handled by a site is always affected by the program. The percentage lets you apply the comparison only to qualifying or captured material.

What does a negative savings result mean?

It means the entered program water intensity is higher than the baseline for the applicable tonnage. The result is a modeled increase in water use, not a calculation error.

Does this estimate include upstream water footprints?

Only if your intensity inputs include them. If the values are based on on-site meters, the result should be interpreted as an operational water comparison rather than a full life-cycle footprint.

Can the result be converted to cost savings?

Yes, but water and sewer tariffs vary and often include fixed or tiered charges. Apply an appropriate marginal water cost to the gallons saved if you want a separate financial estimate.