Draft Guidelines for the Reuse of Greywater in Western Australia

7. DESIGNING A GREYWATER SYSTEM
7.1 General
To design a greywater system, use of these guidelines is recommended. It may be
appropriate for persons contemplating a greywater reuse system to consult a wastewater
system designer or other suitably qualified person to consider the options available.
Greywater systems will not be permitted where Local Government finds that the
installation of a system is not in accordance with these Guidelines and where:
●
●
●
Insufficient property area is available;
Inappropriate soil conditions exist;
The system design is not one approved by the Executive Director, Public Health (see
section 9.3); or
● The property is in an environmentally sensitive area (see section 3.8).
To design a greywater system an estimation of greywater generation is required and the
site then needs to be evaluated for the land irrigation system.
7.2 Calculating Greywater Quantities
To estimate the quantity of greywater generated in a household follow the steps below:
First calculate the number of occupants of a home as follows
2 persons for first bedroom
1 person per additional bedroom
Next calculate each person’s daily greywater flow allocation as 112 litres per day*
(* based on 12L for kitchen, 38L for laundry and 62L for bathroom)
Greywater flow is based upon the number of bedrooms rather than the actual number of
people who currently occupy a dwelling, because the number of bedrooms will remain
constant, while the number of people may vary over time.
DRAFT
Draft Guidelines for the Reuse of Greywater in Western Australia
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