Wastewater usage charges for non-residential customers policy

Policy document number: 765658 Version: 5 Last updated: 31 August 2026

1. Overview

1.1 At a glance

Our policy explains how we apply wastewater usage charges to non-residential customers bills.

1.2 Scope

Our policy covers all non-residential customers (including exempt properties) who discharge to our wastewater (sewerage) system.

The following properties are not subject to wastewater usage charges:

• residential properties
• non-residential properties within a mixed-use development
• each child property in a joint sewerage services arrangement
• small boarding houses
• unmetered non-residential properties (unless they attract a measured wastewater usage charge).

1.3 Objective

Our policy explains when and how wastewater usage charges are applied to non-residential customers, including how discharge factors may be adjusted.

2. Policy in detail

2.1 Background

We provide a wastewater acceptance service to residential and non-residential customers. We apply both wastewater service and wastewater usage charges to non-residential customers.

Wastewater service charges are allocated to non-residential customers based on:

• the water meter size
• the use of the service as calculated from the wastewater usage discharge factor (WUDF), historically referred to as a sewerage usage discharge factor (SUDF).

Wastewater usage charges are applied to non-residential customers only, and are based on how much wastewater you discharge to our systems. Under clause 5.12(2) of the Sydney Water Customer Contract, we determine a WUDF which is used to calculate wastewater service and usage charges for non-residential customers. Current wastewater service and usage charges are available under Business pricing.

2.2 Discharge allowance

Until 1 July 2020, all non-residential and exempt properties that were individually metered received a daily discharge allowance.

Customers who shared a common meter or were on a joint meter service only received one discharge allowance on the common meter or metered property.

From 1 July 2020, the wastewater discharge allowance no longer applies. All non-residential properties are liable for the wastewater usage charge, except for properties listed in section 1.2.

2.3 Wastewater usage charges

The wastewater usage charge for a non-residential property without a discharge meter, is calculated as follows:

Wastewater usage charge = (W x WUDF) x UC

W = the water used (in kilolitres) by the non-residential property for the meter reading period (asrecorded through all our water meters, including both drinking and recycled meters).

WUDF = the wastewater usage discharge factor for that non-residential property.

UC = the wastewater usage charging rate for the meter reading period.

When the wastewater discharge is directly measured through discharge meters, the usage charge is calculated as:

Wastewater usage charge = V x UC

V = the volume discharged through the discharge meter(s) plus an estimated volume for any discharge from toilets and showers

UC = the wastewater usage charging rate for the meter reading period

2.4 Wastewater usage discharge factor

A wastewater usage discharge factor (WUDF) is used to estimate the volume of wastewater discharged to our wastewater system from a non-residential property. It is used to calculate the wastewater usage charge for properties that do not have discharge meters.

The WUDF is also used to determine a property's wastewater service charge. More information on wastewater service charges is available under Business pricing.

The WUDF is the estimated amount of wastewater discharged from the property as a proportion of the incoming volume of water to the property (as measured by your Sydney Water meter/s). It is expressed as a percentage as follows:

WUDF = Volume of wastewater discharged X 100

total water use (as measured by Sydney Water's meters)

We determine WUDFs based on:

• an established property rating standard
• discharge meter readings
• site-specific calculations provided by your representative and agreed by us
• our site-specific calculation.

We apply a WUDF to all new non-residential properties (except for properties listed in section 1.2) that is based on the rating of the property. We have standard WUDFs for different property types. We list common property types and their standard WUDFs. Where a property type doesn't have a standard WUDF, we apply a default of 78%. The WUDF that applies to a particular non-residential property is displayed on the bill.

In certain circumstances, you will need to install a discharge meter to measure the volume of wastewater being discharged, rather than using a WUDF to estimate the volume. For example: where there are large seasonal fluctuations or no fixed correlation between the volume discharged to the wastewater system and the water supplied to the site, you must install and maintain a discharge meter or alternate sub-metering arrangement (e.g. check water meters) that we've approved. We may also include an estimated discharge volume from toilets and showers where appropriate.

Alternate water sources (not supplied by us) can contribute to wastewater discharge volumes and must be considered in calculating the WUDF. Examples of these types of arrangements include:

• onsite collection and reuse
• stormwater harvesting
• sewer mining
• importing liquids from other sites
• bore water.

Where non-metered water sources contribute to the wastewater discharge, the calculated WUDF may exceed 100% of the metered water consumption. While we limit WUDFs at 100% when calculating service charges, we calculate wastewater usage charges using the full measured discharge volume where the sitehas discharge meters.

2.5 Adjustments to WUDFs

If you don't have a discharge meter, we will apply standard WUDFs based on your property rating type. More information about standard WUDFs is available at Non-residential wastewater charges.

We may review the assigned WUDF for a property if:

• you believe your on-site processes are sufficiently different from the standard and the existing WUDF results in you being over-charged for wastewater usage
  You will need to provide sufficient supporting information to enable us to reassess your WUDF, generally representing a minimum of 12 months typical business operations, as detailed in Appendix 1. You can request a review of your WUDF once a year.
• we have revised wastewater discharge information for a specific property rating type, and we apply the revised WUDF to relevant properties
  If we vary the discharge factor by 10% or more for a particular property rating type, we'll inform you at least three months before the amended charges are implemented
• we become aware of factors that suggest an existing WUDF does not accurately reflect the activities on a specific property
  This could arise, for example, when the business activities on the site have changed due to improved processes, a different business type or a change in tenant. We'll determine an appropriate WUDF for the site based on the information and data you provide about your activities over the past 12 months. We'll write to you about the change and the effective start date.

2.6 Implementation of adjusted WUDF

In accordance with clause 5.12(2) of the Customer Contract, any change in the assigned WUDF will apply from either the beginning of the next charging period after you have provided valid evidence for any adjustment or after the expiry of the notice period we communicated to you under clause 5.2 of the Customer Contract for any adjustment we initiated.

We'll evaluate the evidence provided as efficiently as possible given the circumstances of each case. Where this evaluation process extends beyond the billing period and results in an adjustment being in your favour, an appropriate financial adjustment will be made for any affected billing periods following the billing period in which you submitted the evidence.

We won't make financial adjustments to wastewater usage charges already billed or for the billing period in which you submitted the evidence.

You have a responsibility to notify us of any significant changes in business operations that may influence the volume of wastewater discharged to our sewer when the current WUDF applied to your property is no longer accurate.

2.7 Disputes

If you wish to dispute the WUDF assessment, you need to contact us. We'll treat this as a complaint and will manage it in accordance with our established complaints process.If you are not satisfied with our response after it has been escalated to a manager for review, you can contact the Energy and Water Ombudsman (EWON) on 1800 246 545 for external dispute resolution.

3. Definitions

Appendix 1 – Customer-requested WUDF review

A1.1 Principles and assumptions

We operate under a 'user pays' principle which is embedded in the pricing structure as determined by IPART. This principle applies to all customers.Residential customers pay for their use of the wastewater system through an embedded wastewater usage component within their wastewater service charge, on the basis that residential wastewater discharge is relatively stable irrespective of variations in water usage. Residential customers do not pay an additional wastewater usage charge.

Non-residential customers should also contribute equitably to the costs associated with our operation of the wastewater service by paying appropriately for the volumes of wastewater that they discharge.

In principle, the volume of water consumed by a non-residential property can be highly variable and is determined by the activities conducted on the property. The volume of wastewater discharged by a non-residential property is determined by the processes that use the water and is therefore assumed to be proportional to water consumption for most non-residential properties. The Wastewater Usage Discharge Factor (WUDF) reflects this assumption of proportionality. The use of a WUDF as the basis for wastewater charging aligns with recognised good practice in non-residential wastewater management and is a requirement under clause 4.8 of our Customer Contract.Charging for the volume of wastewater that is discharged provides a pricing incentive for non-residential customers to optimise their water management in a way that reduces wastewater discharge.

A1.2 Data to support WUDF review

We seek to use the most up-to-date and accurate information available to set and review WUDFs in situations where direct measurement of discharge volumes is not appropriate for either technical or financial reasons. WUDFs are based on an assessment of the activities carried out on a property. The assessment that we carry out is based on the information that we have about the activities carried out on the property, and the associated likely pattern of wastewater discharge.

We recognise that there are some situations where a business activity may be operated in a way which is different from the assumed profile, and that there may be reason to adjust the WUDF based on more accurate and complete information. The process described below allows a you to provide the information that we require to determine what WUDF should be assigned to a specific property, including the requirements that apply for supporting evidence under different scenarios.

The most accurate way to determine a property's WUDF and volume of wastewater discharged to sewer is through direct metering of wastewater discharge. However, we recognise that direct measurement of wastewater discharge volume can be technically challenging in some circumstances and may not be financially viable where the estimated daily discharge volume is low. The following table sets out the data or information that you will need to provide to us to facilitate a WUDF review, depending on the specific circumstances of your business operations. It references the average daily metered consumption of water on a property to indicate the level of rigour required to justify an adjustment of the WUDF.

Note: Metering is considered to not be financially viable where the annualised 5-year cost of ownership (including installation, certification, ongoing maintenance, and annual calibration) of an approved metering solution exceeds 12 months of standard wastewater service and usage charges for the property.

A1.3 WUDF variation request form

The WUDF variation request form (49 KB, XLSX) is used to capture details of all relevant water inputs and outputs on the property, including those outputs that do not go to our wastewater network. We will use the information provided by you, using this form, as the basis for calculating the applicable WUDF for your property.

The WUDF variation request form is provided as a spreadsheet, with appropriate validation to help you provide high quality and complete information in the first instance. It is designed to ensure that you properly consider all relevant factors when documenting your water use.

Where expected wastewater discharge volume is low (associated with metered daily water consumption of less than 7 kL), the data provided using the form will be accepted as the basis for the calculation of the WUDF. For other scenarios, where your daily water use is above 7 kL, the form can be a valuable tool to guide your collection of the relevant information. We will advise you of the evidence that you will need to provide to support your request for a review.

A1.4 Alternatives to direct discharge metering

Where you are unable to install a discharge meter on each wastewater connection to our network, we can use two general methods to calculate a WUDF:

• You can install sub-meters to measure the water used in systems or processes that do not discharge to our wastewater system. These volumes are subtracted from your metered water supply volume to establish the WUDF. Examples include:
  - irrigation, watering or misting systems,
  - processes such as ice making where all water is fully consumed by the product produced,
  - onsite reuse and/or wastewater management that is not connected to our network.

• You can meter the actual discharge of wastewater from each system or process. The individually metered process discharge volumes will be aggregated to calculate the total discharge volume from these processes. This calculation may include an estimate of the volume discharged from toilets and showers.

In some cases, both above methods will be used to properly account for water used and wastewater discharged to calculate an appropriate discharge factor.

Where the average daily water use is greater than 12 kL, any agreed method of indirect measurement must be certified as complete and accurate by a hydraulic consultant.

A1.5 WUDF review considerations

We will assess each request based on the nature of the business activities carried out on the property and the information provided in the request. When determining our requirements for adjustment of the WUDF, we may consider factors such as (but not limited to):

• the seasonality of business operations
• unusual aspects of the business operations when compared to industry standards for the relevant business type
• recent water consumption patterns
• the most appropriate metering approach given the characteristics of each property.

A1.6 Customer obligations for reviews

You can request a review of your WUDF once each year. When you request a review of your WUDF, you will be responsible for:

• arranging installation and calibration of the metering systems according to our requirements
• providing documentation from a suitably qualified person to show that the metering design is comprehensive and appropriate to accurately account for all wastewater discharges to our wastewater network
• all costs associated with the installation, calibration, and ongoing maintenance of any such meters
• any costs incurred in collecting, analysing and supplying the required information to us to support the reassessment of the WUDF, including costs associated with engaging a third party to verify the method used to derive an alternative WUDF.

Any evidence submitted by a customer to support the requested adjustment of the WUDF must be accepted as valid by us prior to adjustment of the discharge factor based on that evidence.