Buying a home with a sewage treatment plant: what to check before you sign

Buying a home with a sewage treatment plant: what to check before you sign

Why it matters

A standard building and pest inspection does not assess the treatment plant or the irrigation area. Too often, buyers discover a poorly performing system only after they move in, and face an unexpected repair bill.

When a failed plant must be replaced on an established property, the old tank is usually broken up and removed and a new system installed in its place, which can cost more than $10,000. The cost rises further if the irrigation area has to be relaid, or if subsurface drip lines have blocked because the system’s filtration was removed.

What to ask the seller or agent

• The make and model of the plant, and roughly how old it is.
• The service history. Councils require home treatment plants to be serviced regularly by a licensed service technician, and a service report (Form 11) is submitted to the council after each service. Ask to see recent reports.
• Council approval records or plans for the system, if the seller holds them.
• Any repairs or pump-outs and when they were last carried out.
• Whether a service agreement is in place. Our annual agreement stays with the property if it is sold.

What to look at when you visit

• Whether the tank lids and control box are accessible, rather than buried under soil, mulch, pavers or pot plants.
• Whether an alarm light is showing on the control box.
• Any sewage or rotten-egg odour around the plant or yard.
• Boggy, odorous or unusually lush green patches, or water pooling, in the irrigation area.
• Sprinklers or drippers that look broken, blocked or buried.

These are only signs. A treatment plant can look fine from the outside and still be struggling, which is why a proper inspection is worthwhile.

What a pre-purchase inspection covers

Our inspection covers the treatment plant and irrigation area only. It is not a building, pest, plumbing-compliance or electrical inspection.

• The plant: the visible condition of the tanks, lids and risers; the air blower, pumps, alarms and floats; the chlorinator and disinfection.
• Performance on the day: effluent clarity, pH, residual chlorine and temperature, and sludge levels where the tanks can be safely opened.
• The irrigation area: sprinklers, drippers and visible pipework, signs of ponding, run-off or effluent leaving the property, and signage.
• A written report with photos, setting out any issues and the repairs or maintenance we recommend.

It does not include anything underground or hidden that cannot be seen without digging, dismantling or pumping out, laboratory or electrical testing, or checking the system against its original council approval unless the records are supplied. No inspection can guarantee that a system will not fail in future.

Cost and timing

The fixed price is $295 everywhere we work, with no GST added. The written report and photos arrive by email within 2 business days. Cancellation is free until 24 hours before the inspection. Book it alongside your building and pest inspection, and tell us your finance, building and pest, and settlement dates so we can work to them.

See the full inspection details or call 0495 096 532.

By Joshua Smith, QBCC licence PD52825. Updated 20 October 2026.