What Melbourne's water companies expect of businesses
Trade waste needs permission
South East Water says a business that prepares or cooks food, cleans dishes or washes up needs a commercial trade waste consent. Yarra Valley Water says discharging trade waste without an agreement or consent is an offence under section 178 of the Water Act 1989.
Grease traps run on a schedule
South East Water typically requires a pump-out every four months, and Greater Western Water typically every three. Your own consent or agreement sets the actual interval.
Backflow tests are yearly
All three companies expect testable backflow devices on higher-risk sites to be tested at least once a year. Greater Western Water and Yarra Valley Water both want the results sent to them.
Existing gas appliances stay
The Government says there are no changes to end-of-life replacement rules for gas appliances in existing commercial buildings. New commercial buildings go all electric from 1 January 2027, except industrial, manufacturing and agricultural ones.
Your water company's rules at a glance
| Trade waste and grease traps | Backflow devices | |
|---|---|---|
| South East Water | A commercial trade waste consent and an appropriately sized grease trap, pumped out by a licensed waste transporter. Your plumber applies to connect the trap to its sewer. | Devices at medium and high risk properties are registered with it and tested at least annually by a plumber endorsed for backflow testing. |
| Yarra Valley Water | A Trade Waste Agreement. An under-sink grease trap needs its written approval before installation, or it has to be removed at your expense. | A testable device at the meter is tested every 12 months by an accredited backflow plumber, and the results go to Yarra Valley Water. |
| Greater Western Water | A trade waste consent for food businesses producing waste water. Only a licensed plumber can install the grease trap. | The owner arranges an annual test by a licensed plumber. The form is due within 14 days, or a retest may be arranged at your cost. |
Before a fit-out or a new lease
The grease trap's size comes out of the trade waste application, and its position needs the council's nod: all three companies tell businesses to check the location with the council. Yarra Valley Water notes that some tenancies share a communal grease trap that the body corporate should manage. If you're not sure whether the site has one, ask the landlord or body corporate, or get a licensed plumber to check.
Grease trap waste isn't a job for staff. Yarra Valley Water says emptying a grease trap yourself is against the law, and only EPA-approved waste transporters may do it. Greater Western Water puts the onus on the business to book an EPA-licensed collector at the frequency in its agreement.
Hot water in aged care, childcare and health settings has stricter temperature limits. The national commercial plumbing page covers those, and our backflow testing page explains the devices.
Questions for a commercial plumber
- Is our grease trap the size our trade waste consent or agreement requires?
- Who lodges the plumbing application or approval with the water company?
- Can you test our backflow device and send the report to the water company for us?
- Which class of work are you licensed for, and does it cover this job?
What we would do
Confirm which water company serves the site before anything else, because its rules decide the grease trap, the paperwork and where the backflow report goes. Keep the trade waste consent or agreement, pump-out dockets and test reports in one folder. Book testing and trap work outside trading hours where you can. Then stay with one plumber who learns the site, and we'll match you with one who takes on commercial work in Melbourne.