Australian Water Management Review Vol. 1 2014 | Page 99

Assumptions:

Water usage per household vs Water runoff from lot

600

Runoff from ground surfaces per year
Potential roof water capture per year

500

2010 household usage

• 1/3rd roof area, 1/3rd paved,
1/3rd garden/lawn
• Runoff coefficients: roof 0.85,
paved 0.8 and garden/lawn 0.2

400
Volume (kL)

• Allotment size 750 sq.m.

• Water restrictions applied for
some Cities in 2010
300

• Warrnambool water consumption
from 2009/10
• Using historical average rainfall
and typical temporal patterns

200

100

0
Canberra

Brisbane

Adelaide

Sydney
Capital City

Perth

Melbourne

Warrnambool

Figure 2. Comparison of available roof water to residential demand

copy), allowing the program to be run a PC using
Microsoft operating systems. It has a self-contained
help menu to guide users through its use.
Using the Toolkit
The toolkit has been designed with the flexibility
for a range of roof water harvesting systems to be
defined with different arrangements for the transfer
pipelines, storages and treatment plant. By ticking a
‘check box’, the system components can be included
or excluded from a particular scenario. The transfer
pipelines can be configured to suit gravity or
pumped pipelines.
Data Input
• Collection System – the location of the
development, development scale and other
collection network design parameters are input
using 4 data input screens
• Storages – the capacity and configuration of the
storages are input on a single screen.

implemented in Warrnambool. It allows for
construction cost variation across Australia by
applying appropriate cost factors and rainfall
variation using different temporal rainfall patterns
and spatial annual rainfall data from the Bureau of
Meteorology.
The toolkit is for preliminary screening of options
on a relative cost basis and should not be used as a
design or cost estimation tool. Calculations rely on
a number of assumptions and relationships derived
from limited data sets. Results are suitable for
preliminary screening only and should not replace
a more detailed assessment by an appropriately
qualified and experienced person.
The toolkit is available on CD from Wannon
Water (visit www.wannonwater.com.au to order a

• Pipelines – the single input screen allows for a
gravity or pumped pipeline to be selected.
• Treatment Plant – again this element can be
included or excluded from the toolkit calculations
depending on whether investigating treated or
untreated water supply options.
Data Output
The toolkit calculates the volume of water spilt
from the storages, the water transferred along the
various elements and a yield from the system.
The yield is compared to the annual demand for
these propert