If your business discharges anything into the sewer that isn’t ordinary domestic wastewater, you need a trade waste agreement with your water authority before you start discharging. Not after opening. Not when someone complains. Before.
That single sentence is what most businesses find out in the wrong order, and the cost of finding out late is almost never the approval itself. It’s the concrete you have to cut.
Who this actually applies to
Trade waste catches far more businesses than people expect. Food premises are the obvious one, but the requirement extends to mechanical workshops, vehicle wash facilities, manufacturers, printers, laboratories, dental and medical practices, hairdressers and beauty salons, and any site with a wash bay or hardstand that drains to sewer.
The test isn’t your industry. It’s what leaves your premises and enters the sewer. Grease, solids, oils, chemicals, metals, plaster, amalgam or anything at a temperature or pH outside the normal range will generally require both an agreement and a pre-treatment device installed before the connection point.
Your authority depends on where you are. South East Water covers the south east and bayside, Yarra Valley Water the north and east, Greater Western Water the west. Requirements and what they will accept differ between them, so confirm with yours rather than relying on what a mate in another suburb was allowed to do.
The order it usually happens
Here’s the sequence we’re called into most often.
A tenant signs a lease. The fit-out is designed around the kitchen or workshop layout the business wants. A builder is engaged. Slabs go down, walls go up, equipment is ordered. Somewhere near the end, a plumber or a council officer asks whether trade waste has been approved. It hasn’t. Nobody’s applied.
At that point the required device has to be retrofitted into a building that’s already finished. That usually means cutting the new slab, relocating drainage, redesigning the back of house layout to find the space, and delaying opening while an application is assessed. The business is also paying rent throughout.
None of that cost is the trade waste requirement. All of it is the sequencing.
The order it should happen
Before you sign the lease. Ask what the premises is currently approved to discharge. A site previously used as a retail shop has no trade waste infrastructure at all. A site previously used as a café may have an arrestor that’s undersized for what you intend to do. This is a question for the lease negotiation, not for later.
At concept design. Bring a licensed plumber in while the layout is still on paper. The size of the device you need is calculated from your fixtures, equipment and expected load, and that number determines how much floor space and depth you have to give up. It’s far easier to design a kitchen around a known arrestor size than to find room for one afterwards.
Before construction. Lodge the application. Your authority will generally want plans showing the proposed device, its location and the drainage layout. Approval takes time, and it is not a formality.
During construction. Install to the approved plans. Variations made on site without going back to the authority are a common reason for sign-off being refused later.
Before you open. Get the connection inspected and the agreement finalised. Then set your servicing schedule, because the agreement carries ongoing obligations, not just an installation requirement.
If you’re already trading without one
Contact your water authority rather than waiting to be found. Authorities generally deal more constructively with a business that comes forward than one discovered through an inspection or a downstream blockage traced back to your premises.
The practical question is what can be retrofitted with the least disruption, and that’s genuinely site-specific. In some cases there’s an achievable solution. In others the honest answer is that the layout has to change. Either way, knowing early is better than being told during a shutdown.
Where we see this most
Trade waste problems cluster in particular parts of Melbourne, and for different reasons.
In the industrial estates around Dandenong, Braeside, Carrum Downs and Scoresby, it’s usually a change of use. A tenancy built for storage becomes a manufacturing or processing operation, and the drainage was never designed for what’s now going down it.
In workshop suburbs like Bayswater, Rowville and Seaford, it’s wash bays and hardstand areas draining to sewer without silt or oil separation.
In research and clinical facilities around Clayton, it’s the specialised discharge that comes with laboratory work, where the requirements are stricter and the consequences of getting them wrong are more serious.
Frequently asked questions
Do I need trade waste approval if I’m only doing a small fit-out?
Possibly. The requirement is based on what you discharge, not the size of the works. A small café can trigger it while a large office won’t.
Who applies, the landlord or the tenant?
Usually the occupier, but the lease may say otherwise and the landlord often has to consent to the works. Check both before assuming.
How long does approval take?
It varies by authority and by complexity. Treat it as something to start early rather than something to fit into the last fortnight of a build.
Can you help with the application?
Yes. We prepare the plumbing documentation authorities require and manage the application alongside the installation. Get in touch to talk through your site.
