Find out how we calculate the wastewater usage charge and wastewater service charge for non-residential customers using your wastewater usage discharge factor (WUDF).
WUDFs and your bill
The WUDF determines your wastewater service charge. It is also used to estimate your wastewater usage charge if you don't have a discharge meter.
The charges set by the Independent Pricing and Regulatory Tribunal (IPART) for the wastewater service charge are based on a WUDF of 100%. We apply the specific WUDF for each property to calculate its individual service charge.
See help to read your non-residential bill to locate this information.
Wastewater usage charge calculation
Your wastewater usage charge is $1.50 per kilolitre of your wastewater discharge. It's based on how much it costs to transport and treat each kilolitre of wastewater discharged from your site.
If you don't have a discharge meter, we calculate your wastewater usage by applying a wastewater usage discharge factor, or WUDF. The WUDF is a percentage of the water that your water meter shows has been delivered to your site.
To estimate the WUDF, we consider the volume of water that is:
- used in products
- evaporated through air conditioning
- used for irrigation
- used for other purposes.
We've identified standard WUDFs for a range of common property types. We'll use a standard WUDF unless:
- you provide information about your operations that would justify your property having a different discharge factor
- your property has a wastewater discharge meter.
Do you need a discharge meter?
If a WUDF calculation doesn't represent your actual wastewater discharge, you can install a wastewater discharge meter.
Note that wastewater discharge meters are compulsory for industrial trade wastewater customers and have additional conditions.
| Property types | Standard WUDF |
|---|---|
Commercial | 95% |
Industrial / Industrial strata unit | 95% |
Government | 95% |
Public charity | 95% |
Church property / Place of worship | 90% |
Commercial with one or more cooling towers | 78% |
Public reserve | 50% |
To review your standard WUDF
If you think a standard WUDF doesn't apply to your property (and you don't have a discharge meter), complete a WUDF variation request form (49 KB, XLSX). Please provide evidence to support your request in line with requirements detailed in Appendix 1 of our Wastewater usage charges for non-residential customers policy. You can request one free review each year.
Wastewater service charge calculation
Your wastewater service charge is directly linked to the size and number of water meters on your site. For non-residential customers, it is also based on the WUDF. Below are some of the common meter and WUDF combinations and their charges. These charges relate to individual meters only.
| Common meter size | Maximum quarterly wastewater service charge | Common WUDF | Charge that appears on the bill |
|---|---|---|---|
20 mm | $177.56 | 95% | $168.68 |
20 mm | $177.56 | 78% | $138.50 |
20 mm | $177.56 | 50% | $133.17* |
25 mm | $277.44 | 95% | $263.57 |
25 mm | $277.44 | 78% | $216.40 |
32 mm | $454.56 | 95% | $431.83 |
* The minimum wastewater service charge applies instead of the calculated amount of $88.78.
Minimum and maximum charges for 2026–27
The minimum wastewater service charge is $133.17 per quarter, regardless of meter size. This is the 20mm service charge with a WUDF of 75%.
The maximum charge, with 100% WUDF applied, is based on 92 days. Quarters with fewer days will cost less.
Typical example of charges
A commercial building has one 80 mm water meter and uses 1,000 kilolitres (kL) of water in a 92-day quarter. The industry standard wastewater usage discharge factor for a commercial property is 95%.
Quarterly wastewater charges
- Quarterly service charge for an 80 mm meter x WUDF of 95%
$2,840.98 x 95% = $2,698.93 - Wastewater usage charge is the volume discharged to sewer estimated by the WUDF
1,000 x 95% = 950 kL - Volume discharged x current wastewater usage charge
950 kL x $1.50/kL = $1,425 - Quarterly service charge + wastewater usage charge = Total
$2,698.93 + $1,425 = $4,123.93