A building inspection is standard when buying a property in Australia. But what most buyers don’t realise is that standard building inspections typically don’t include a thorough plumbing assessment. They’ll note whether fixtures exist and if there’s visible damage, but they won’t run cameras through your sewer line or pressure test the pipes.
That’s a problem. Plumbing repairs are among the most expensive surprises a new homeowner can face, and the issues that cost the most are usually the ones you can’t see from the surface. A cracked sewer line, corroded pipes behind walls, or a hot water system on its last legs can turn a dream purchase into a financial headache within weeks of settlement.
Here are the plumbing checks every buyer should do before signing, and which ones are worth paying a licensed plumber to handle.
1. Check the Hot Water System
The hot water system is often the single most expensive plumbing component in a home. Most systems last 8 to 12 years (sometimes up to 15 with good maintenance), and replacing one can cost anywhere from $1,000 to $3,500 or more depending on the type.
What to look for:
- Find the unit and note the brand, model, and serial number. The serial number usually contains the manufacture date.
- Check for rust, corrosion, or leaks around the base and fittings.
- Turn on a hot tap and check how long it takes to heat up, whether the temperature is consistent, and whether the water runs clear (brown or rusty water is a red flag).
- Ask the seller how old the system is and whether it’s been serviced.
If the system is over 10 years old, factor in a replacement cost when negotiating the purchase price. You may not need to replace it immediately, but it’s coming. If the system is already showing signs of failure, check out our guide on what to do when your hot water system stops working.
2. Test the Water Pressure
Low water pressure isn’t just annoying. It can indicate undersized supply pipes, partially blocked lines, corroded internal pipework, or a leak somewhere in the system.
What to do:
- Turn on multiple taps and the shower at the same time and see if the pressure drops significantly.
- Test both hot and cold water separately. If hot water pressure is low but cold is fine, the issue is likely with the hot water system or its supply line rather than the mains.
- Check pressure on both levels if it’s a two-storey home. Upper floors naturally have slightly lower pressure, but a big difference warrants investigation.
Consistently low pressure across the property is worth flagging with a plumber before you commit.
3. Inspect for Visible Leaks and Water Damage
Walk through the property with fresh eyes and look specifically for signs of current or past water damage:
- Under sinks: Open every vanity and kitchen cupboard. Look at the pipes and connections for drips, moisture, staining, or warped timber.
- Ceilings and walls: Water stains (yellow or brown patches), bubbling paint, or peeling wallpaper near bathrooms and kitchens indicate leaks from above or within the wall.
- Around toilets: Check the base of every toilet for moisture, soft flooring, or discolouration. A toilet that keeps running after flushing may have a faulty flapper valve wasting water constantly.
- Flooring: Warped timber, lifting tiles, or damp carpet near wet areas are all signs of water getting where it shouldn’t.
Previous water damage that’s been painted over or patched can be hard to spot. If something looks recently repaired in a wet area, ask why.
4. Flush Every Toilet and Run Every Drain
This sounds basic, but many buyers skip it. Flush every toilet in the house and watch what happens:
- Does it flush fully on the first attempt?
- Does the cistern refill quickly and stop running?
- Is there any gurgling from other drains when you flush? (This can indicate a venting issue or partial blockage in the sewer line.)
Run water through every sink, shower, and bathtub. Watch how quickly it drains. Slow drainage across multiple fixtures usually points to a downstream blockage rather than an individual drain issue, and that can mean problems in the sewer line.
5. Ask About the Sewer Line
The sewer line is the big one. It’s underground, out of sight, and expensive to repair or replace if it’s damaged. Tree root intrusion, ground movement, age-related cracking, and poor original installation are all common causes of sewer line failure, particularly in older homes.
A CCTV drain inspection is the only reliable way to assess the condition of the sewer line. A licensed plumber inserts a small camera into the pipe and records footage of the entire line from the house to the street connection. This reveals:
- Root intrusion
- Cracks, breaks, or collapses
- Bellied (sagging) sections where waste can pool
- Joint displacement
- Build-up or partial blockages
A CCTV inspection typically costs between $200 and $500, which is nothing compared to the $5,000 to $20,000+ it can cost to repair or reline a damaged sewer pipe. If you’re buying an older property (anything built before the 1980s), this inspection is not optional. It’s essential.
6. Look at the Pipe Material
If you can see exposed pipes (in the garage, under the house, or in the ceiling cavity), take note of what they’re made from:
- Copper: Durable and long-lasting, but older copper can develop pinhole leaks from corrosion, especially in areas with aggressive water chemistry.
- PVC/UPVC: Standard for modern drainage and some water supply. Generally reliable.
- Galvanised steel: Common in homes built before the 1970s. These pipes corrode from the inside out, restricting flow and eventually failing. If you see galvanised pipes, budget for a full repipe at some point.
- Polybutylene (grey plastic): Used in some Australian homes from the 1970s to 1990s. Known for becoming brittle and failing at joints. If present, get a plumber’s assessment on remaining lifespan.
- Cast iron: Used for older sewer lines. Can last decades but eventually corrodes. Worth a camera inspection.
The pipe material tells you a lot about the future maintenance costs you’ll be taking on. If the sewer line is damaged, pipe relining is often a faster and less disruptive repair option than traditional excavation.
7. Check the Stormwater System
Stormwater drainage is easy to overlook, but poor stormwater management causes foundation problems, flooding, and erosion over time.
Walk around the property after rain if possible, or check for:
- Gutters and downpipes connected and in good condition
- Downpipes directed away from the foundation (not dumping water against the house)
- No pooling or standing water around the property
- Stormwater pits and grates clear of debris
If stormwater drains into the sewer system (which it shouldn’t), this is a compliance issue that will need rectifying.
8. Check for Backflow Prevention
If the property has a garden irrigation system, fire hose reel, or any connection that could allow contaminated water to flow back into the drinking supply, it should have a backflow prevention device installed. Many the Central Coast councils require annual testing and certification of these devices.
Ask the seller whether backflow devices are installed and whether they have current test certificates. If they don’t, you’ll be responsible for getting compliant after settlement.
Get a Pre-Purchase Plumbing Inspection
You can (and should) do the visual checks yourself, but a professional pre-purchase plumbing inspection covers what your eyes can’t. A licensed plumber will pressure test the system, run a CCTV inspection on the drains and sewer, assess the hot water system, and provide a written report detailing any current issues and upcoming maintenance needs.
This report gives you negotiating power. If the inspection uncovers a damaged sewer line or a hot water system that’s past its use-by date, you can request repairs before settlement, negotiate a price reduction, or walk away from the sale with confidence that you’re avoiding a money pit.
A comprehensive pre-purchase plumbing inspection typically costs $300 to $600. For the peace of mind and the leverage it provides in negotiations, it’s one of the smartest investments you can make during the buying process.
Don’t Skip the Plumbing
A property can look perfect on the surface and have thousands of dollars in hidden plumbing issues. The cost of finding out after settlement is always higher than the cost of finding out before. Do the checks, book the inspection, and make your purchase decision with full visibility of what’s happening behind the walls and under the ground.
Miracle Plumbing offers pre-purchase plumbing inspections with CCTV drain assessments. If you’re buying a property and want to know exactly what you’re getting into, get in touch before you sign.
