What this tool does
Shows whether the entered reusable supply covers a site-specific weekly landscape demand and how much area that supply can support.
When to use it
Use after estimating supply and obtaining local reference ET, effective rainfall and a defensible plant factor for one hydrozone.
Inputs and supported units
Each labelled field explains the quantity it expects. Unit-system changes convert existing numeric entries once and keep calculations on a single SI internal basis. Supported shared units include L/min and GPM, metres and feet, kPa and psi, millimetres and inches, kW and hp, and °C and °F as relevant.
Calculation or decision method
One millimetre over one square metre equals one litre. EPA's water-budget method likewise treats climate, plant type, area, rainfall and efficiency as separate inputs.
How to interpret the result
Read the primary result with the supporting breakdown and warning. A plausible number is not evidence that every input, operating case or design constraint has been included.
Worked example
150 L/day over 100 m² with 35 mm/week ETo, plant factor 0.4, 2 mm effective rain and 80% efficiency supplies about 70% of the 1,500 L/week gross demand.
Assumptions
Entered fixture, event, climate, soil and tariff values describe the planning case; volumes are kept on an SI internal basis.
Limitations
The result is a preliminary quantity or cost screen. It does not approve a source, end use, plumbing connection, treatment process, setback, storage time or irrigation method.
Sources
- San Francisco Public Utilities Commission — Graywater Design Manual
- Washington State Department of Health — Greywater Reuse
- U.S. EPA WaterSense — Water Budget Tool
- Australian Government — Australian Guidelines for Water Recycling