City West Water’s vision is to be an exceptional service provider that puts customers first and benefits the community.

Together with Melbourne Water, South East Water and Yarra Valley Water we are working to improve the way salinity is managed in recycled water. One way we are doing this is by changing how we monitor for salinity in trade waste and the sewerage network.

We are proposing an alteration to the Trade Waste Approved Acceptance Criteria from Total Dissolved Solids (TDS) to Sodium:

Current TDS Acceptance Criteria:

1.2 (d) The total mass load of total dissolved solids must not exceed 200 kg/day.

Proposed Sodium Acceptance Criteria:

1.2 (d) Where the total mass load of sodium exceeds 1,000 kg/day, the concentration of sodium must not exceed 270 mg/litre.

This will target sodium as the parameter within TDS that presents the greatest risk to soils and plants irrigated with recycled water, and offer:

  • a cost and time saving for a number of Trade Waste customers
  • the ability to focus non-compliance and risk management activities toward the higher risk discharges
  • more meaningful information for risk assessments

The Essential Services Commission (ESC) regulates the metropolitan Melbourne water businesses and is responsible for approving any amendments to our Approved Acceptance Criteria. Prior to submission of any proposed amendments, we are required to consult with customers and stakeholders who may be impacted by the changes.

Most trade waste customers won’t notice any impact due to these changes.

Impacted customers will receive a letter that explains the changes and their impacts and, for those who will need a sodium Customer-Specific Assessment Criteria, we will be making a time to discuss the changes with you and obtain your feedback.

Further information is provided in the More Info section below.

Have Your Say

We value your feedback and want to hear your thoughts on this matter. Feedback will be used to inform the proposal we will submit to the ESC and our implementation plan, which will include:

  • Sampling requirements
  • Agreement updates
  • Interim arrangements

To have your say, please complete the short survey below, or share your thoughts in the discussion forum.


City West Water may publish your feedback on our website. Please check below if you give permission to have your company name quoted or you prefer to remain anonymous. Required
Do you understand why TDS and Sodium are managed? Required
Would you like to see the removal of the TDS limit? Required
Do you think there should be a new Acceptance Criteria for Sodium? Required
Do you think the limits (270mg/L & 1000kg/day) are reasonable? Required
Do you think recycling waste water is an important issue? Required
Do you like this method of consultation for proposed changes to Acceptance Criteria? Required
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Discussion forum

More Info

What is Trade Waste?

Trade waste is liquid waste from commercial businesses and industry that is discharged to sewer in accordance with City West Water requirements. More info:

What are Approved Acceptance Criteria?

Approved Acceptance Criteria are concentration or load limits for a range of parameters, which businesses must meet in order to discharge trade waste to sewer. The Acceptance Criteria ensure that trade waste does not pose a risk to health and safety, the sewerage transport and treatment system, or the environment, or impede recycling. City West Water may accept trade waste that does not meet the Approved Acceptance Criteria under certain conditions.

What are Customer-Specific Acceptance Criteria?

Customers who are not able to reasonably achieve the standard Approved Acceptance Criteria are able to apply for Customer-Specific Acceptance Criteria (C-SAC). An assessment is made to ensure that risks remain acceptable and that the customer has reduced the parameter as far as practicably possible. Conditions, such as additional monitoring, may be imposed.

Why is there currently an Acceptance Criteria for Total Dissolved Solids?

Total Dissolved Solids (TDS) is a measure of all the dissolved organic and inorganic material present in the water, including salt. Dissolved Solids that enters the sewer pass through a sewage treatment plant, prior to discharge of the treated waste water to the environment. If the water is low in salt, it can be re-used beneficially, to irrigate pastures and crops.

However, a high salt load in the water can damage the receiving soil and/or the plants being irrigated. TDS monitoring can identify the source of salts in the sewerage network.

Why the switch to Sodium?

Total Dissolved Solids includes components that are treatable (organic) and non-treatable (inorganic) via conventional biological treatment processes. Sodium is a component of inorganic TDS.

Expert advice is that managing sodium instead of TDS targets the parameter which presents the greatest risk to soils and plants irrigated with recycled water; Trade Waste Approved Acceptance Criteria should reflect this. Other components of inorganic TDS include calcium, magnesium and chloride; the first two are largely beneficial salts and the latter is usually associated with sodium.

By implementing and enforcing a Sodium Acceptance Criteria, we will be better targeting non-compliance management and focusing on the largest customers where a change in sodium load could make a difference to the overall risk level whilst significantly reducing the administrative burden for other customers.

What will change for me?

The only customers who will be affected by the proposed change at this time are Trade Waste customers who currently discharge high loads of Total Dissolved Solids to the sewer.

Customers who routinely discharge TDS loads above 200 kg/day hold a Customer-Specific Acceptance Criteria (C-SAC). If the current TDS limit is removed and a Sodium limit introduced, only a small number of customers will exceed the new Sodium limit (>1000kg/day & >270mg/L). These customers will be granted a Sodium C-SAC at the time of the AC change, with the same end date as the TDS C-SAC being removed. The concentration and load limits will be determined based on best available data and will reflect the customer’s current discharge requirements.

Customers who hold a TDS C-SAC but won’t exceed the proposed Sodium limits, will have the TDS C-SAC removed from their Agreement.

Self-monitoring (sampling) for Sodium

Sodium will be added to all composite sampling programs, either at the time of the change or upon agreement renewal. Sodium and chloride will be added to snap sampling programs for any customer holding a Sodium C-SAC, as well as for those whose monitoring history or activities suggest their trade waste contains elevated sodium concentrations or loads.

Who else is involved?

This proposal applies to the whole Melbourne Metro catchment so Yarra Valley Water and South-East Water are consulting with their customers also. Collectively we are working with Melbourne Water as it treats the majority of the sewage and supplies the recycled water. The Essential Services Commission is the regulator and has been consulted throughout. The Environment Protection Authority has also been consulted with because of its interest in salt being discharged to land.

What are the Essential Services Commission’s requirements?

In order to introduce new or alter existing Acceptance Criteria, City West Water must gain approval from our regulator the Essential Services Commission, whose Trade Waste Customer Service Code protects customer interests. The submission to the ESC needs to include details of an impact assessment, customer consultation, and implementation plan.

What will this cost my business?

This consultation process is being conducted at no charge to City West Water customers.

If approved, the removal of Total Dissolved Solids C-SAC will be performed at no charge to customers.

If a sodium C-SAC is required, it will initially be applied at no cost, however future renewals will be billed as per the standard C-SAC administrative process.

Sampling costs may vary, dependent on what you already sample for.

How does this affect my charge for inorganic TDS load?

At this point in time no changes are being made and, if you are currently charged for your inorganic TDS load, you will continue to be. We are currently preparing our Pricing Submission for mid-2018 to mid-2023 which may contain proposed changes. We are consulting on the Pricing Submission separately.

When will the change be applicable?

It is anticipated that the new Acceptance Criteria will be applicable in October 2017, subject to the Essential Services Commission's approval.