Repiping Older Christchurch Homes: Galvanised, Copper and PEX

Why galvanised steel fails

Galvanised pipe is steel with a zinc coating. Once that coating wears through, usually from the inside where you can't see it, the steel beneath starts rusting and the internal diameter of the pipe narrows with corrosion buildup.

That's what causes the classic symptoms: brownish water when a tap is first turned on, pressure that's dropped noticeably over the years, and pinhole leaks that appear at joints and low points as the pipe wall thins from the inside out.

Signs it's time to repipe

• Discoloured or rusty-tasting water, especially from hot taps or after the house has sat unused
• Two or more unrelated leaks in the pipework within a year or two
• Noticeably lower water pressure than when the fittings were new
• Visible corrosion or scaling on exposed pipe under the house or in the ceiling
• A pre-purchase inspection flagging galvanised pipe as due for replacement

Copper vs PEX

Copper has been the standard replacement for galvanised pipe for decades. It's rigid, long-lasting, handles heat well, and most Christchurch plumbers, including us, have decades of experience installing and repairing it.

PEX (cross-linked polyethylene) is a flexible plastic pipe that's become common in newer installations. It's quicker to install because it can be run in longer lengths with fewer joints, it doesn't corrode, and it copes well with the ground movement that's been an ongoing issue in Christchurch since the earthquakes, since it can flex slightly rather than crack at a rigid joint.

Choosing between them

• PEX is generally faster and less invasive to install, which matters in an occupied home
• Copper has a very long track record and is often preferred for exposed pipework where appearance and durability matter
• PEX's flexibility can be an advantage under a house with a history of ground movement
• Cost differences vary by job, we'll quote both where it's a genuine option

Full repipe vs partial repipe

A full repipe replaces every water pipe in the house and is usually the right call when galvanised pipe is failing throughout. A partial repipe targets a specific run, for example just the hot water line to a bathroom, and can make sense when the rest of the system is in reasonable condition or budget is staged over time.

We'll assess the whole system on-site rather than just the pipe you called about, because a partial fix on a system that's failing everywhere often means repeat callouts.

What a repipe involves

• Mapping the existing pipe runs, including any hidden under gib or in the subfloor
• Isolating and draining the old system before cutting in the new pipe
• Running new pipe with minimal wall and ceiling disturbance where possible
• Pressure-testing the entire new system before handover
• Making good any gib, access panels or flooring disturbed during the work

Timing it around other renovation work

If you're already planning a bathroom or kitchen renovation, or opening up walls for other work, that's the ideal time to repipe the affected sections, since the access is already there. It's worth raising it with us early if you know your home still has galvanised pipe.

Frequently asked questions