Copper Vs Plastic Piping – Water Pipe Replacement Wellington
This page is a discussion comparing Copper Vs Plastic.
Wellington homes use a mix of copper, plastic, polybutylene, and older galvanized iron piping. Each material performs differently, and ageing systems can lead to leaks, poor pressure, and ongoing failures. Our qualified plumbers specialize in the replacement of old or failing water pipes, providing safe, compliant upgrades for all property types.
Copper Piping
Copper is durable and heat-resistant, but in Wellington it can still fail when electrolysis or mixed-metal corrosion occurs. Pinhole leaks and internal corrosion are common signs that replacement is needed.
Copper can have problems with water treatment where and aluminium flocculant is used to treat water, and some of it gets into the water supply system. Where this happens it causes corrosion. This is due to Aluminium being at the other end of the Electrochemical series ie it attacks copper. It is mostly a hot water cylinder problem where they are copper.
Plastic Piping
Modern plastic piping performs well, but earlier products—especially polybutylene, early models of Buteline, Polytherm, and Dux Qest (Quest)—are now prone to cracking and joint failure. Many Wellington homes still contain these materials, making them a priority for replacement. Ensure the old piping over 25 years old has pressure limiting valves to restrict pressure to as low as possible. Keeping the pressure to around 300 kPa will limit leakage.
Galvanised Iron
Although 0lder homes may have galvanised iron it is no longer an approved material for potable water supply. Many homes experience rusting, blockages, and bursts, particularly in soft-water areas. Full replacement is usually the most effective solution. Often iron pipes leave a stain on baths and basins. The stain is difficult to remove. Often buildings that have iron piping find that suddenly the water is cut off unexpectedly due to rust breaking off and travelling along till it cannot go any further causing a blockage cutting off the water either to the whole building or part of it. This will require re-piping.
Why Pipes Fail
- Electrolysis and corrosion.
- Ageing polybutylene systems over 25 years.
- Excessive Pressure and temperature changes.
- Ground movement
- Internal rusting of galvanised iron
Wellington’s Pipe Replacement Specialists
We replace all types of water piping, including polybutylene, Dux Qest, Dux Black, galvanised iron, and compromised copper. Our team ensures your new system meets NZ Standards, improves water pressure, and provides long-term reliability.
If your home has leaking pipes, poor pressure, or known polybutylene, contact our expert plumbing team for a water pipe assessment and replacement plan.
Copper Vs Plastic
Call today 0800 484 353
Poor Shower Pressure Wellington
If you have poor shower pressure and a low-pressure hot water system, you need 20mm copper. The pipe should run from the supply tank or pressure-reducing valve to the shower mixer for best results.
Southern will only repipe in PEX or copper. For in ground water supplies, we replace in high-density Polyethylene. We recommend using these materials as they are tested to last a long time, are reliable, and durable.
Copper Vs Plastic Call today 0800 484 353
The Polybutylene Disaster
One leak in the plastic pipe can cost you a lot of money. A small leak can result in a big problem. A Wellington owner went away on holiday for a month and came back to the ceilings in his home collapsed, and the lower part of his house flooded. A lot of damage was done in his absence, the family heirlooms were ruined and half of the house was destroyed.
The Real Cost of Polybutylene is huge
The house was unliveable for weeks. A large part of what he lost was not covered by insurance, as money cannot replace items of sentimental value, for example, family photos.
Consequential Damage
Some insurance companies do not cover dux qest polybutylene piping where there have been bursts before. Some insurance companies are not covering it at all.
Some homeowners wait till the pipe bursts, thinking that the insurance company will pay. Most insurance companies don’t cover the Polybutylene pipe they cover consequential damage.
This is and image of a Buteline Elbow where the insert leg has broken off due to age. This kind of failure is becoming more common.
When we undertake repairs, some wall linings have to come out while replacing the plastic pipe. Plumbing in front of the wall also needs to be removed and restored. We cannot reinstall some plumbing items. For example, vanities are glued in or of poor construction. Some shower cubicles cannot be taken out without damage.
Polybutylene
Polybutylene pipe is the most common water supply pipe in NZ. It is also convenient for the plumber as it is lightweight, needs simple tools, and not a lot of skills to install it. The disadvantage of installing Plastic pipe is that rodents chew it, and it splits and cracks over time. In the past, Dux had a version called Qest, often spelled wrong as Quest.
Black Qest Piping
The black Qest plastic water pipe was installed all over New Zealand, including Wellington, Lower Hutt, Upper Hutt, Karori, Khandallah, Tawa, Brooklyn, Kapiti Coast, Mount Victoria, and Whitby. The acetal fittings were more prone to leakage. More recently the piping itself is failing, both the black and grey, and all brands. We can do a lot of things to minimize the replacement cost of this pipe.
It generally pays to replace the lot in one go. Replacing it piece by piece is more expensive. It is usually run along a cheaper route to minimize reinstatement of wall linings.
Brands of Polybutylene –
- Dux Qest (no longer available) – Black
- Dux Secura and Secura Gold – Grey
- Buteline – Grey
- Hep2O – Dark Brown
- Speedfit – Grey
- Polytherm – Grey.
Current Project – December 2025
This month we are repairing a polybutylene piping system where the damage over a period of years has rotted the flooring to the point it is dangerous to enter the bathroom. In order to work in there we have to put a sheet of ply on the floor. Although polybutylene seems cheap at the time it is installed in the long run it is the most expensive. It is likely when the floor comes up when the owner can afford to do the work the structure of the building may be damaged and need replacement.
Are There Places Where Copper Cannot be Used
There is an area called Kapiti where copper has a problem with corrosion. A conclusive cause has not be found. In this case plastic wins the Copper Vs Plastic debate.
Copper Vs Plastic
Copper usually wins.
Replacing Polybutylene
Copper Vs Plastic
You dont have to use copper or polybutylene to replace it. There is a new material now Polypropylene or PEX which is a better quality product than polybutylene. The fittings are better too, more robust. The pipe is often double wall. It is much tougher than polybutylene.
The best product for water supply is High-Density Polyethylene (HDPE). This has been used for many years and is good for cold water but not for hot water. Polypropylene is good for hot water, hence is used inside. It is slightly more expensive than Polybutylene. It still can be chewed by rodents, but it won’t fail the way polybutylene fails.
We are experts at replacing polybutylene. We have completed many burst pipe jobs in Wellington.
The cost of replacement depends on where it is installed. If it is under the house or in the roof space and if it is accessible, then the cost is fairly low. There is just the piping in the walls to deal with which involves opening up wall linings in some cases. If it is between the floor then ceiling needs replacement too. We usually pick a different route to that which was originally used to minimise reinstatement.
We recommend copper and PEX to replace all internal piping. Some of the grey piping is also now splitting and leaking, we recommend replacing it with polybutylene. Call Southern now on 0800 484 353 for a consultation on Copper Vs Plastic and check out our free quote terms and conditions.
Copper Piping
Copper Vs Plastic
If you want the best flow and peace of mind from rodents, then replace plastic with copper. It is rare for copper to burst. If it fails, it is usually a pinhole. The disadvantage of copper is that it is a bit more expensive and can suffer from electrolysis. The level of failure is low. It copes well with high-temperature hot water and rodents. Some hot water piping can only be done with copper.
PEX v’s Polybutylene
These two piping systems are both plastic. Polybutylene has been around for many years here in NZ. PEX has been around for many years overseas and is a much better quality product than polybutylene.
PEX Cross Linked Polyethylene
We use Rifeng PEX, Kembla PEX, and Kekekit PEX. All are European standard products.
PEX has a thicker wall and is generally a tougher product. PEX and polybutylene rely on a crimp ring. If you do not like a crimp ring, we can install PEX with a sliding sleeve. Polybutylene has a shorter life than PEX and a much higher failure rate.
Call today for an appraisal on a Pex installation 0800 484 353
The Cost of Water Leaks
In Wellington, only commercial properties require water meters. Polybutylene fails at a higher rate than other products. It is often used underground, and the leaks go undetected. They can be detected if a water meter is fitted or the leak comes to the surface.
Case Study 1
One of our customers had water under their deck and thought it was ground water and thought they needed a ground water drainage system. We started work on this but noticed the water was getting beyond normal. A pressure test was carried out on their water piping and it was found to be leaking at a huge rate. The leak was traced and repaired. This meant the ground water drainage system was no longer needed. The job was a good example of why water meters can save a lot of water.
Case Study 2
One of our customers was paying thousands per year in water charges. We questioned the high bill and did a pressure test. The test confirmed pipes were leaking. We replaced the piping for the entire commercial property. They saved a lot of money per year from their Body Corp fees. This enabled them to put the money into other building maintenance.
Case Study 3
Another house in Karori had a huge leak that came to the surface. They thought this was caused by the surface water running off. The leaks had been going for several months.
Polybutylene has a limited life 20-30 years approx, less if used on hot water and the pressure is high. It may last longer if the water is cold and the pressure is low.
Southern plumbers are experienced in resolving water pipe leaks and installing or upgrading water pipes. We undertake both commercial and residential projects. Call us on 0800 484 353 for all kinds of plumbing services in Wellington.