# IWM
Integrated Water Management (IWM) places water security, liveability and the health of waterways and landscapes at the heart of servicing our urban communities.
The average Victorian household uses approximately 150,000 litres of potable (drinking) water each year, or around 160 litres per person per day (ABS, profile.id.com.au and water.vic.gov.au, 2021). Up to 90% of that water consumption is used for toilet flushing, garden irrigation and other uses that don’t require water of drinking quality. Simple design decisions can reduce consumption of drinking water and help to conserve Victoria's precious water resources.
Increasing urbanisation (including greenfield and infill development) has resulted in a dramatic increase in areas of hard and impermeable surfaces, such as buildings, roads and car parks. Most rain that falls in urban areas becomes run off, which carries pollutants from the hard surfaces into the stormwater system and then into local waterways and impacts people, plants and animals. Designing buildings to reduce stormwater runoff improves the quality of our waterways.
In the Integrated Water Management category, BESS includes actions regarding the water efficiency of fixtures, rainwater collection & use, water efficient landscaping, building systems water use and stormwater treatment.
Other water efficiency considerations that are not captured in BESS but are also important include:
- Locating hot water units close to the point of use to reduce heat loss through pipes.
- Locating wet areas (bathrooms & laundries) and kitchens adjacent to each other.
Other stormwater considerations that are not captured in BESS but are also important include:
- For industrial developments - containing polluting activities within the canopy line or within a bunded area
- Installing gross pollutant traps where hardstand paving drains to SW system
- Installing pervious paving where appropriate
Our Integrated Water Management Fact Sheet (opens new window) can help you with design strategies for your development.
# Project Profile
These questions are applicable to the whole site.
Do you have a reticulated third pipe or an on-site water recycling system?
Where the site will connect to a reticulated third pipe or an on-site water recycling system is to be installed, the details of this should be provided with the BESS report.
A third pipe system is also known as a 'purple pipe' system. It is a Class A recycled water supply that can be used for toilets, laundry and irrigation water needs.
A grey water system would be an example of an on-site water recycling system.
In BESS, rainwater tanks are not classed as on-site recycled water systems. Go to the Rainwater tank profile to enter rainwater tanks.
Refer to your council and water authority for details and requirements related to these systems.
If you click yes here, the Recycled third pipe / on site water recycling system profile will appear and you can fill out details of the third pipe or on-site water recycling system.
Are you installing a swimming pool?
This question is for information only. It is not connected to any calculation within BESS.
# Stormwater profile
You can opt to use the Melbourne Water STORM tool or other modelling software such as MUSIC to achieve IWM credit 2.1 Stormwater Treatment.
When selecting the Melbourne Water STORM tool, then input the STORM score achieved from the STORM tool.
When selecting to use MUSIC or other modelling software, then enter results from the modelling including:
- Flow (% Reduction)
- Total Suspended Solids (% Reduction)
- Total Phosphorus (% Reduction)
- Total Nitrogen (% Reduction)
In the Stormwater category, BESS includes actions regarding stormwater treatment. You must meet the Urban Stormwater Management Best Practice standards for water quality (CSIRO, 1999), e.g. through min 100% STORM score, or compliant MUSIC model.
# Recycled third pipe / on site water recycling system profile
The Recycled third pipe / on site water recycling system profile is activated when you answer Yes to this in the Integrated Water Management profile. To complete the Recycled third pipe / on site water recycling system profile you will need:
The irrigated garden area (in square metres) connected to reticulated third pipe or an on-site water recycling system only (i.e. not also connected to rainwater system). This includes automatic and manual irrigation systems.
Whether the irrigated garden area if a water efficient garden. Your answer here affects the calculation of water used for irrigation purposes. A water efficient garden includes low water use plant selection and specifying water efficient irrigation (e.g. drip irrigation with timers and rain sensors).
Whether there is other external water demand connected to the reticulated third pipe or an on-site water recycling system only (i.e. not also connected to rainwater system) such as bin wash down or pool top up. You are required to estimate this water usage in litres per day. Additional water uses include non-potable demands such as pools, commercial process uses and taps for washdown.
# Rainwater tank profile
You can add rainwater tanks by clicking on the “Add Rainwater Tank” button. This activates the Rainwater tank calculator.
This table allows for one or more tanks to be included by clicking on the 'Add Rainwater Tank' button.
To complete the rainwater calculator you will need the following information:
- The roof area connected to the tank. The term 'roof area' is used here for simplicity - you should include the total catchment area connected to the tank. Assess your roof plans to determine which roof areas are able to be connected. Water runoff from trafficable areas is considered stormwater, so should not be included as rainwater.
- The tank size. Do not include any tank volume that is required for on-site stormwater detention, as this volume is released slowly back into the stormwater system.
- Whether the tank will be connected to the reticulated third pipe or onsite water recycling system.
- The irrigated garden area connected to the tank. This includes 'active' (automatic and manual irrigation systems) and 'passive' irrigation (where water leaks from the tank into the garden).
- Whether the irrigated garden area if a water efficient garden. Your answer here affects the calculation of water used for irrigation purposes. A water efficient garden includes low water use plant selection and specifying water efficient irrigation (e.g. drip irrigation with timers and rain sensors).
- Whether there is other external water demand connected to the tank such as bin wash down or pool top up. You are required to estimate this water usage in litres per day. Additional water uses for rainwater include non-potable demands such as irrigation, pools, commercial process uses and taps for washdown. Tank water will only be available for additional uses if it not required for internal uses.
# Setting up rainwater tanks for grouped dwellings
If you have set up your project with grouped dwellings, you will be entering water fixtures and fittings for that group. This includes the rainwater tank connection.
In this case, you will need to create a rainwater tank that has the combined tank area and the combined connected roof area (and the combined garden area connected, if relevant).
# Water Fixtures, Fittings and Connections
This table lists the grouped dwellings and spaces as they were initially entered in the project details stage.
You are required to select the efficiency of all the water fittings and appliances, and then identify where any rainwater or other non-potable water source is being used in the building. Eg toilets, washing machines, hot water. Check with your Council whether this option is accepted. If you plan to have an additional alternative water source as a back up to your rainwater tank, BESS will not allow you to select ‘hot water’ as an option for your rainwater tank to connect to.
Rainwater connected to: Toilets
To answer 'yes', at least one toilet per dwelling must be connected
Rainwater connected to: Laundry (Washing Machine)
To answer 'yes', at least one pair of washing machine stop cocks per dwelling must be connected
Rainwater connected to: Hot Water
To answer 'yes', all other hot water connections must be connected.
When entering information in this table you can select the ‘Select all’ button is the top left-hand corner of the table to copy a selection across all columns.
# Default and Scoping out
For default and scope out options within the water fixtures, fittings and connections table, the following guidance is provided:
- For residential developments, when dishwashers and washing machines are not being provided as a part of the build, these should be entered as ‘Default or unrated’.
- For residential developments it would be reasonable to scope out urinals.
- For non-residential spaces, when a kitchen is not being provided the dishwasher can be scoped out.
- For non-residential spaces, when washing machines are not being provided these can be scoped out.