Is greywater legal in residential homes?

Civil & DrainageWater Conservation & Reuse

Greywater System Savings Calculator

Calculate potential annual water savings, sewer bill reductions, and system payback periods from residential greywater recycling.

Civil & Drainage Field StandardsWater Conservation & Reuse

Engineering formulations calibrated to IPC, UPC & NEC specificationsSub-Zero Cold Climate Tolerances

Quick Summary & Key Answer

A 4-person household generates roughly 120 gallons of reusable greywater daily (over 43,000 gallons per year) from washing machines and showers. At standard utility rates ($9.50 per 1,000 gallons combined water/sewer), a greywater system saves approximately $415 to $500 per year.

Greywater accounts for 50-65% of residential indoor wastewater.
Kitchen sink and toilet water is blackwater and cannot be used in greywater systems.
Sub-surface mulch basin discharge prevents human and pet contact with greywater.

Interactive Calculator

Adjust inputs for real-time results

Number of Household Occupants

Greywater Sources Captured

Combined Water & Sewer Rate per 1,000 Gallons$/1k gal

$/1k gal

Calculated OutputWater Savings Calculated

Annual Water Bill Savings

$416/year

Annual Greywater Reused: 43,800 gallons
Daily Greywater Harvested: 120 gal/day
10-Year Cumulative Utility Savings: $4,161

Note: Laundry-to-Landscape systems divert rinse water to mulch basins around fruit trees and ornamental shrubs without pumps.

Plumbing Code Greywater Guidelines

Uniform Plumbing Code Chapter 15 governs residential greywater diversion valves and underground mulch infiltration trenches.

Frequently Asked Questions

Common questions regarding this calculation and code compliance

Yes, most states permit unpermitted laundry-to-landscape gravity diversion systems provided water is discharged into sub-surface mulch basins.