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Introduction to Plumbing Gasfitting and Drainlaying


In generic terms, and certainly in an historical sense, the term "plumber" covers a wide ranging industry, or set of industries. A plumber's job incorporates a large number of activities requiring a great variety of skills. Although a traditional plumber's trade is now commonly broken down into a number of more specialised trades, a modern plumber still requires a broad knowledge and considerable skill.

Most people historically link plumbers with water and pipes, and many will be aware that the word 'plumber' is derived from the Latin word plumbum, meaning lead. Using this soft and malleable material, early plumbers manufactured many products including pipes and containers, and learnt to apply sheets of lead to weatherproof buildings. They developed methods of reticulating water and removing waste products, as well as heating water for public baths. Plumbers also built hot air systems for heating buildings.

Lead pipe bath

As cultures evolved, many of these skills were passed on to new tradespeople but, in some cases knowledge was lost and skills died out. Over time, with the invention and development of new technologies pipes were used to transport an ever increasing variety of materials, including fuel gases and chemicals.

As new technologies developed into entire new industries, new skills and solutions were needed. For example, early windows were made of small panes of glass held together and sealed with lead strips - the work of plumbers; further development of leadlight windows led eventually to the trade now called glazing. Until very recently, in some parts of the world including Britain, part of the plumber's trade included fitting glass window panes.


In the early days of motor vehicle manufacture, the fuel lines (pipes) were run by plumbers. Plumbers were also responsible for installation of the acetone generators and the copper pipes feeding acetylene to headlights. To top that off, when the first metal-clad motorcars were damaged, plumbers were called on to repair the panels using 'wiping metal', which plumbers traditionally used for joining lead pipes. It was not until the 1920's that the new trade of panel beating broke away from plumbing, as the damaged-car industry grew large enough in its own right.

In a similar vein, when this newfangled electricity needed to be installed in buildings, the wires were run through metal conduits - the entire job initially being done by plumbers. Plumbing text books as late as 1920 still had entire sections devoted to electrical wiring and electricity generation, which was still considered plumbers' work.

Heating and ventilating has always been considered part of a plumber's job, and in many parts of the world is still considered an integral part of the trade. However, a variety of technologies, developed in response to different environmental conditions and population densities, have led to divergent geographical regions developing a multitude of solutions to this work. For example, in many parts of the USA, plumbers are responsible for air conditioning, while elsewhere a separate trade of HVAC (Heating, Ventilating and Air Conditioning) has been established. In New Zealand, many solid fuel heaters are installed by plumbers, but this is not the case elsewhere.

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Gasfitting and Roofing

Gasfitting has always been associated with plumbing, because it has always incorporated pipe fitting and water heating for homes. Many countries still incorporate gasfitting within the plumbing trade, but in recent years there has been a trend towards specialisation. Most apprentices in New Zealand still serve Plumbing and Gasfitting apprenticeships, but many opt out of gasfitting, or later tend to specialise only in plumbing.

Britain has long separated gasfitting from plumbing, as they have with Heating and Ventilating. In Britain (and some other countries), gasfitting has been further broken down into a number of different specialisations, each requiring a separate licence or qualification.

Roofing is another industry which has largely split off from plumbing and diversified. The first metal roofs were made from lead, and were thus plumbers' work. Then when new metal materials like zinc, copper, and later galvanised steel were introduced, plumbers installed these materials too. However, in many countries roofing is considered a separate trade. In some instances different trades are responsible for the installation of different types of roofing material.

In New Zealand, most metal roofing is still installed by plumbers except in the larger cities, where specialised roofing companies have sprung up. However, it is fair to say that even among these specialist roofing firms, most flashings, and more complex metal roofs, are still undertaken by qualified plumbers. This is especially notable in the collection and disposal of rain water, and the installation of various gutters, spouting and downpipes.

Hot Water Service

A number of factors have also led to a divergence of technologies around the world. In the USA for instance, most domestic hot water systems use storage water heaters - what we are familiar with as hot-water cylinders in New Zealand. In most European countries, however, "instantaneous water heaters", pioneered by Junkers and Bosch in Germany, are the prevalent means of hot water production. These are now becoming very popular here, and to a lesser degree in Australia.

In Europe, most central heating systems are "wet" systems using radiators (and more recently, under-floor pipes), but in North America (including Canada), "dry" (hot air) systems are more common.

In large parts of Asia, local plumbers only install cold water systems. The hot water service is often provided via a centralised plant. In some cases no hot water is available at all except for a small "end of service" water-heater feeding only one fixture.


Drainlaying is not often seen as a separate trade in other countries, and is sometimes done by a general builder. In Australia 'drainers' are simply a sub-trade of plumbing; all plumbers being required to qualify as drainers as part of the general "sanitary plumbing" qualification. New Zealand is one of the few countries to recognise drainlaying as a separate trade.

The New Zealand Context as can be seen then, the definition of plumbing, and therefore plumbers work, is not universal. That is why many people from overseas who see themselves as "qualified plumbers" are surprised to find that their qualification is not recognised in New Zealand. This is not just because the practical skills expected of a plumber in New Zealand often differ from those in other countries, but also because our many rules and regulations are also vastly different from those which have evolved in other countries.

Overseas plumbers, with in some cases upwards of 30 years experience, may never have installed a low pressure hot water system. Often they will never have used many of the materials and systems used in this country. They will also be unfamiliar with our system of "performance-based standards", and our many means of compliance based on the Building Act - a method of regulating the building process foreign to most tradespeople from overseas. Therefore, before being allowed to practice in New Zealand, overseas trained and qualified plumbers and gasfitters are required to demonstrate a knowledge of New Zealand systems and legislation. Only then can they be registered to work unsupervised.

You can find more details under the Information and Opportunities tabs at the top of this page.

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