When building, redeveloping or significantly extending a property, you need to demonstrate how your plans maintain the health and functionality of waterways and catchments by implementing water sensitive urban design (WSUD) principles. This applies to all residential, commercial and industrial developments.
The key principles of WSUD are to:
- reduce the demand for potable (fit for drinking) water by using alternative sources of water such as rainwater and treated wastewater, and encouraging water efficient appliances
- minimise wastewater and treat wastewater to a suitable standard for re-use and/or release to receiving waters
- treat urban stormwater to a quality where it can be reused and/or discharged to surface waters
- use stormwater in the urban landscape to improve the visual and recreational amenity of developments.
More information about WSUD considerations for different development types are available below.
You can also use our calculators to identify how the water efficiency targets can be met. The calculators have been designed specifically for the Canberra region using local water usage statistics, rainfall data and watering requirements.
WSUD options for single residential developments
The Residential Zones Technical Specification guidance on how you could reduce the amount of water you use at home.
The following options meet the specification for single residential buildings:
Option A: Water storage and connections
| Block size | Minimum tank size (litres) | Minimum roof area connected to tank | Tank connected to at least*: |
|---|---|---|---|
| Compact blocks < 250 m2 | Nil | Nil | Nil** |
| 250 to 500 m² | 2,000 | 50% or 75m² | Toilet, laundry cold water, all external uses |
| 500 to 800 m² | 4,000 | 50% or 100m² | Toilet, laundry cold water, all external uses |
| 800 m² | 5,000 | 50% or 125m² | Toilet, laundry cold water, all external uses |
*The connection must have a pump that can't be elevated to give adequate pressure.
**At least 3 star WELS rated plumbing fixtures
Review the Rainwater tanks - Guidelines for Residential Properties in Canberra [3.6 MB] for advice about installing a rainwater tank.
Option B: Greywater system, treating water to Class A standard
All bathroom and laundry greywater should be captured, and all toilets, laundry cold water and external uses must be connected to greywater.
Review the Greywater use - Guidelines for residential properties in Canberra [1.2 MB] for ways to re-use water from laundries, kitchens and toilets.
Option C: Alternative ways to meet the water reduction targets
By using the calculator below, to show the development can reduce how much mains water it uses by 40%, compared to a similar development built in 2003. The development can meet this target without relying on landscaping to reduce consumption.
WSUD for multi-unit residential, commercial and industrial developments
Design and construction professionals can refer to:
- The ACT Practice Guidelines for Water Sensitive Urban Design – Module 2: Designing Successful WSUD Solutions in the ACT
- Plumbing Note 24: Grey water drainage separation and provision for rainwater plumbing (single residential buildings)
- The calculators below.
Waterways calculators
Use this spreadsheet to calculate the water consumption of commercial, industrial or institutional developments with and without water saving features.
Download the calculator [13.7 MB]
Information you will need
To use the spreadsheet calculator, you will need to know:
- the number of bedrooms
- the water rating for shower head, dishwasher, toilet/urinal, tap fittings and clothes washer
- the site area
- total roof area
- all rainwater tank information
- all grey water system information
- any swimming pool, spa or pond information
- the lawn area
- the garden area
- the impervious surface area
- stormwater retention targets (find out more about stormwater applications)
- net conditioned floor area
- the approximate water consumption of the cooling system and the fire testing system
- the percentage of toilets and urinals connected to the rainwater tanks or grey water system
Use this spreadsheet to calculate the water consumption of a multi-unit residential development with and without water saving features. This calculator covers dual occupancy through to multi-storey apartments.
Download the calculator [13.5 MB]
Information you will need
To use the spreadsheet calculator, you will need to know:
- the number of bedrooms
- the water rating for shower head, dishwasher, toilet and clothes washer
- the site area
- total roof area
- all rainwater tank information
- all grey water system information
- any swimming pool, spa or pond information
- the lawn area
- the garden area
- impervious surface area
Information for multiple rainwater tanks or multiple greywater tanks can be grouped together if the size, collection area and end uses of the water sources are equivalent, for example:
| If... | Then... |
|---|---|
| there are multiple rainwater tanks and they all have 100m2 of roof area flowing into them, they are all 2000L in volume and are all used for garden irrigation, toilet flushing and cold water laundry. | the volumes can be considered as one tank and collection area can be considered as one roof. This principle only works if all of the volumes, roof area end uses are equal. If this is not the case, then they need to be considered separately. |
Use this spreadsheet to calculate the water consumption of single residential dwellings with and without water saving features.
Download the calculator [2.7 MB]
Information you will need
To use the spreadsheet calculator, you will need to know:
- the number of bedrooms
- the water rating for shower head, dishwasher, toilet and clothes washer
- the site area
- total roof area
- all rainwater tank information
- all grey water system information
- any swimming pool, spa or pond information.
Insert these details into the light green cells.
Calculating water ratings
Tap and shower water ratings can be measured by using a stopwatch and a bucket:
- Turn on the tap/shower to full and measure the volume of water used in 15 seconds
- Multiply by 4 to get the water consumption for a minute (L/min)
- Compare this water consumption with the Star rating table located on the indoor tab in the water reduction calculator
Most modern appliances have a water consumption rating.
| Star rating | Water saving |
|---|---|
| 1 star | Little or no water saving features |
| 2 star | Minimal water saving features |
| 3 star | Moderate water saving features, now the minimum standard of water saving required in the ACT for fittings |
| 4 star | Good water saving features |
| 5 star | High water saving features |
