There are two ways of planning your greywater system:

a) by assuming that the system is for you and your family's use (your actual situation);
b) or that the system is intended for the house regardless of who occupies it( i.e.,basing your calculations on the number of bedrooms the house has).

Steps to follow:

1. Take a brief inventory of the house's greywater sources and the number of uses that they get or could get.


gal / person . day


gal / person . day


gal / person . day

Other sources

gal / person . day

Total greywater

gal / person . day

Try to determine how many gals. per cycle your appliances use--or use the short-form sizing estimator below.


Approximate water use of standard appliances

US clotheswashing machine (top-loading)

30 gallons per cycle

European (front-loading) clotheswasher

10 gallons per cycle


3 - 5 gallons per cycle

Low-flow shower head (per shower)

3 - 7 gallons per average use

Other sink use (shaving, handwashing, etc.)

1 - 5 gallons per average use

2. Use the General Site Data and Design Considerations below to determine what steps are relevant for your situation. Give special consideration to the final dispersion of the effluent, making sure that the soil can accept the amount of water that will be generated, treated and discharged (your local sanitation engineer can do a percolation test to determine the ability of the ground to accept water). If water shortage happens to be a particular restriction where you're located, note that greywater filtered through a soilbed of the sort described in this text will not become anaerobic and thus can be saved for [lawn] irrigation.

A. Overall Site Plan

  • Topography
  • Slope
  • Soil Conditions
  • Ledge
  • Groundwater
  • Buildings
  • Utilities
  • Property lines
  • Vegetation
  • Wetlands

B. Regulatory Requirements

  • Plumbing Code
  • State Regulations
  • Reuse Regulations
  • Effluent Discharge Limitations:
    • BOD
    • NO3
    • E-coli
    • other.
  • Land Application Regulations
  • Permit Question
    • Local Board of Health
    • State Environmental Regulations
    • Building Code Requirements
    • Monitoring Requirements
    • Test Data for Approvals

C. Design Information

  • Existing Treatment Facilities
    • Septic Tank
    • Leach-field
    • Cesspool
    • Other
  • Influent Quality and Quantity
    • Number of Bedrooms
    • Number of Persons regulary in residence
    • Occupancy (i.e.,on a year-round or seasonal basis)
  • Type of Appliances and fittings
    • Flow-Rates:
    • Dishwashers
    • Washing machines
    • Bathtubs, showers
  • Evaporation Rates
  • Temperature Data
  • Rainfall Data
  • Effluent Reuse Goals

D. New System Specifications

  • Propose Treatment Train
  • Technical Specifications
  • Effluent Treatment Character -Typical Transformation
  • Reduction in Pollution
  • Production of Fertilizer
  • Reuse Opportunities
  • Optimum Use of Existing Facilities
    • Existing Pipes
    • Dispersion Beds
    • New Use of Existing Equipment
  • Potential for Savings
    • Water
    • Fees - Water and Sewage
  • Overall Improvement Evaluation


3. Check with your local authorities regarding any special/local concerns and regulations. Submit your application to the local board of health or consult your local professional engineer (P.E.) for plans and documents needed for your application (usually a topo-graphic site drawing with pertinent information about your site and the proposed solution). If your local P.E. is unfamiliar with alternative greywater pollution prevention systems (e.g., soilbed treatment), provide her/him with the name of this website or send a copy of this manual.