Greywater Reuse Calculator

Estimate how much water you can reclaim from showers, sinks, and laundry for irrigation or toilet flushing.

Save
gallons
gallons
gallons
%
USD/1000 gal

Daily Greywater Available

39.0 gallons

Annual Greywater Reused14,235 gallons
Annual Water Savings71 USD
Share of Total Water Use32.2 %

Daily Greywater Available vs Water Rate

View formula & how it works →

How to Calculate Greywater Reuse

Greywater is wastewater from showers, sinks, and laundry (not toilets or kitchen sinks) that can be safely reused for irrigation.

Formula

Reusable Greywater = (Shower + Laundry + Sink) * Reuse %

Sources

  • Showers: 20-40 gal/day per household
  • Laundry: 15-30 gal/load
  • Bathroom sinks: 5-15 gal/day

    • Greywater can reduce household water consumption by 30-50%.

    Example Calculation

    A household generating 40 gal shower, 15 gal laundry, 10 gal sink daily, reusing 60% at $5/1000 gal.

    1. 01Total greywater: 40 + 15 + 10 = 65 gal/day
    2. 02Reusable: 65 * 60% = 39 gal/day
    3. 03Annual: 39 * 365 = 14,235 gallons
    4. 04Annual savings: 14,235 * $5 / 1,000 = $71

    Frequently Asked Questions

    Related Calculators

    Daily Water Usage Calculator

    Calculate total household water use.

    Rainwater Harvesting Calculator

    Supplement with rainwater.

    Irrigation Water Calculator

    Calculate irrigation needs.