Selling a house with a septic tank in Australia: the approval that does not transfer, what the buyer's conveyancer asks in each state, and the council checklist that decides the price

Selling or buying a house with a septic tank is not a plumbing problem; it is a paperwork problem with a plumbing bill attached. The system in the ground will be there on settlement day whatever happens. What changes hands, or fails to, is the council’s permission to run it, the record of how it has been looked after, and the knowledge of where the trench is. This guide follows the order in which a conveyancer works, state by state, and ends with the one buyer checklist a council has actually written down.

The approval does not travel with the house

In New South Wales this is explicit. The Onsite Wastewater Management Guidelines of April 2025 give councils a model approval to operate whose condition 2 reads: «This Approval to Operate is valid until the date of expiry on this Approval, or until renewal fees are unpaid, or the system is altered, or the associated buildings are altered, or the system does not satisfactorily pass a council inspection, or the property changes ownership». The last item is the sale. What saves the buyer from an immediate offence is clause 47 of the Local Government (General) Regulation 2021: a person who purchases land with a sewage management facility «may operate a system of sewage management without the approval required under section 68 of the Act for the period of 3 months after the date on which the land is transferred», and «if the person duly applies, within the period of 2 months after the date on which the land is transferred», they «may continue to operate that system of sewage management without approval until the application is finally determined». Three months to run, two months to lodge, and the clock starts at settlement, not at the first council letter. We go through what the NSW approval contains in council approval for a septic system.

In Victoria the structure is different and the documents have names a buyer can search for. The City of Greater Geelong describes a two-stage process under the Environment Protection Act 2017: «A “Permit to Alter/Install” an on-site wastewater management system. This permit must be issued before a building permit can be issued», then «An “Approval to Use” the on-site wastewater management system. This permit must be issued before a building Certificate of Occupancy can be issued by a Building Surveyor». Geelong adds the penalty for jumping the gun: «Using your OWMS before an “Approval to Use” has been issued can result in a penalty infringement notice», and asks for «a minimum of five business days to allow the approval to use to be issued». EPA Victoria’s page, updated 18 May 2025, puts the owner’s standing duty in one line, «keep your onsite wastewater management system in good working order», and names the source, «Part 5.7 of the Environment Protection Regulations 2021», which «local councils can enforce». A Victorian permit can be transferred rather than reapplied for, and councils price it: Yarra Ranges charges $155.00 to transfer a permit to install or alter to a new owner, Mount Alexander Shire $171.49.

Queensland, Western Australia and South Australia do not re-issue the approval on sale; the buyer inherits the file and its conditions. The conditions are where the money is. Gladstone Regional Council: «Yes. All on-site wastewater systems need approval (plumbing permit) from Council», and «Maintaining a treatment plant or sand filter is a legal requirement under the Plumbing and Drainage Act 2018». WA Health, on a page last reviewed on 10 October 2025, lists what you may not do without the local government’s written permission, starting with «Dismantle a wastewater system». Playford, in South Australia, writes the owner’s duties as a list: «Your aerobic wastewater treatment system must be serviced every three months by a licensed service contractor» and «All wastewater system tanks need to be pumped out every four years».

What the buyer’s conveyancer asks, state by state

The questions are the same everywhere; only the names of the documents change.

Two Queensland details decide whether a service history exists at all. Gladstone says the service «report forwarded to the owner and the Council within 10 business days from the date of the service», which means the council holds the history even if the seller has lost it; and «if Council finds a treatment plant or sand filter isn’t being maintained», «enforcement action may be undertaken and penalties applied». A buyer in Queensland can therefore ask the council, not the vendor, whether the quarterly reports exist.

The checklist one council wrote for buyers

Gannawarra Shire, in northern Victoria, published a fact sheet for people «purchasing an established dwelling» that is the most useful page on this subject in Australia, because it asks the questions a contract never does. For sewered towns: «ask the real estate agent or current owner if the property is connect to the sewer», and if not, «factor in the cost of connection when negotiation your purchase price and have the job done as soon as you take ownership», with the warning that a house inside the sewer area and not connected «will be receiving a service fee from Coliban Water merely for making the service available».

For unsewered properties the sheet is a tick list. «What type of waste water system does the property have?» «How old is the system?», with the benchmark that «Most traditional septic systems will operate effectively for around 25-30 years». «Where is the septic tank?» «Can you see it or is it completely covered?» «When was the system (septic tank or aerated waste water treatment system) last pumped out?», with the rule «They should be pumped out every three to five years. We recommend that you have the system pumped out once you move in and then every 3 years». «Where is the disposal field?» «Is water ponding on the surface?», because «If so, the system isn’t working correctly and will require work». «Is water directed off the property?», because «All waste water must be kept on-site – it is illegal to discharge waste water off a property». «If there is an aerated waste water treatment system installed, when was it last serviced?», since «these plants should be serviced every three months», and «Don’t forget to obtain the details for the service agent from the current owner, along with any manuals and records». And two questions about people rather than pipes: «How many people have been using the system for the past few years?», because «A system that has worked happily for years with 1 or 2 people living in the house may not cope with 4 or 5 people using it», and «Is the house empty?», because «You wont be able to tell if the on-site waste water system in operating correctly in a house that isn’t being occupied».

The sheet ends with the sentence every buyer should read twice: «Please be aware that we cannot discuss with you anything about a property that you don’t own». The council will not do the buyer’s homework before settlement. That is what the records search and the inspection are for.

The records search, and what it costs

Victoria’s councils keep the permit and the approval to use on file, and some have a formal way to ask. Mildura Rural City Council requires that the ratepayer «must complete an Onsite Wastewater Management System Search Application» to locate an existing system on a property; the same council’s permit fees show what a new system’s paperwork costs, $844.20 as the statutory fee or $643.30 to alter fixtures only, and a building surveyor there «must obtain a “Report and Consent”» from council before issuing a building permit on an unsewered site. In NSW the equivalent is the council’s own pre-purchase inspection, $427.00 at Port Stephens in 2026/27, which is also the figure we use in the septic system inspection article to show why a building and pest report does not cover the tank.

The search answers the question the Whirlpool thread below could not: whether a permit was ever issued. A buyer who found a tank with its lids buried asked, years later:

The reply he received is the law of every state in one sentence:

When the contract says sewer and the ground says septic

The most expensive mistake in this subject is not a failed trench; it is a wrong tick. A seller on Whirlpool, with settlement set for 16 March and the family on holiday in New Zealand:

The forum’s diagnosis was quicker than the agent’s: «Do you get a bill from your council or water authority for sewage? If it’s only for the supply of water, then it’s very likely that you have a septic system», and the cheap test is a plumber with a camera rather than ground-penetrating radar. The legal position was summarised by another member in a line that applies to both sides of every such contract: «it’s not fair to the buyer either. They bought a place that they thought was connected to the sewer». Gannawarra’s advice to buyers in sewered towns is the mirror image: ask before the offer, price the connection, do it on day one.

The buyer’s version of the same surprise is quieter and more common, a system described by the seller as needing nothing:

An absorption trench system with no service contract can be exactly that, and the replies said so. But «once in the last 5 years» is outside Gannawarra’s three-to-five-year pump-out and the four-year rule of Mitcham, Playford and WA Health, and in NSW the buyer’s own approval to operate will put the system in a risk band with an inspection cycle the seller never mentioned.