How do I know if my pipes are galvanised?
Galvanised steel water pipe was standard in Australian homes from the postwar years into the late 1970s, when copper took over. Look where pipework is exposed: under the house, at the hot water system, at the front garden tap. Galvanised pipe is grey metal, threaded at the joints rather than soldered, and a magnet will stick to it, which it will not do to copper. Rust staining or blistering at the threads is common. Plenty of Gold Coast homes have a mix, where sections were replaced in copper or PEX over the years while original galvanised runs survive in walls and under slabs, and those surviving sections are the ones that cause the trouble.
Why does galvanised pipe fail from the inside?
The zinc coating that gives galvanised pipe its name sacrifices itself to protect the steel. After decades, the zinc is gone and the steel rusts. Corrosion builds inward as scale, narrowing a 20 mm pipe to a fraction of its bore, which is why old homes so often have weak showers and taps that slow to a dribble when a second outlet opens. Eventually the wall thins until pinhole leaks appear, usually at threaded joints where the pipe wall was cut thinnest to begin with. Coastal air and our warm, humid climate do the outside of the pipe no favours either. None of this is a defect you can service away. It is the material reaching the end of its design life.
What are the signs it is time to act?
| What you notice | What it means inside the pipe | Repair or replace? |
|---|---|---|
| Brown or discoloured water after time away | Loose rust picked up from the pipe walls | Plan replacement, monitor |
| Falling pressure, worse on hot | Bore narrowing with corrosion scale | Replacement territory |
| One pinhole leak | Wall thickness locally gone | Spot repair is fine, budget for more |
| Second or third leak within a couple of years | Pipe wall failing generally | Replace, stop patching |
| Rust weeping at threaded joints | Joints corroding through | Replace that run at minimum |
Can I just repair the leaking section?
Yes, and sometimes that is the right call. A single accessible burst on galvanised pipe typically costs $250 to $650 plus parts to repair as of 2026, and if the rest of the system is behaving, one repair with honest monitoring is a fair plan. The trap is repair number three. Each new pinhole is evidence the pipe wall is thin everywhere, and money spent on serial patches would have gone a long way toward new pipe. Our rule of thumb, and we apply it in our own quoting: after the second leak on the same era of pipe, we quote the repair and the replacement side by side so you can see both numbers before deciding.
What does replacing galvanised pipe involve and cost?
Replacement means running new copper or PEX and abandoning the old steel, either in stages or as a whole-house repipe. Staged replacement targets the worst runs first, typically the hot lines, which corrode fastest. A full repipe does the lot in one hit with one round of wall access and reinstatement. Because access, wall construction and pipe layout vary so much between a 1960s Labrador cottage and a 1970s highset in Nerang, we price repipes by inspection and quote a fixed figure, not an hourly rate. Under-slab sections that have failed are their own category, running $1,500 to $4,000 plus when repaired through concrete, which is often the point where rerouting overhead becomes the smarter spend. Replacement also fixes the pressure and water quality problems in one go, which no amount of patching will.
Is replacing galvanised pipe worth it before selling or renovating?
If a renovation is on the horizon, the answer is nearly always yes, because walls open for a bathroom or kitchen are the cheapest access you will ever have to the pipework behind them, and tying a repipe into planned work avoids paying for reinstatement twice. For sellers, building and pest inspectors flag galvanised pipe routinely, and buyers price the risk into offers whether or not the pipes are currently leaking. We see the same story from the other side on pre-purchase inspections: original steel pipework is one of the first things we photograph. Replacing it converts an inspection red flag into a selling point, and unlike most pre-sale spending, it also fixes the showers you still have to use until settlement day.
Rusty water or a repeat leaker in an older home? Call Hills Plumbing & Gas on 0472 657 042 or book at /services/burst-pipe-repairs/. QBCC licence 15243081, fixed quotes for repair and replacement side by side.
Sources: Queensland Plumbing and Drainage Act 2018 (water plumbing is licensed work); AS/NZS 3500 plumbing and drainage standards.