Plumbing and drainage

Common problems include low hot water pressure, and deteriorating pipework – especially if the pipework was upgraded in the upgraded in the late 1970s or early 1980s.

Water supply

Original details

Public water supplies were generally available in New Zealand cities from the 1880s and a reticulated water supply was universal to houses in urban areas by the 1930s.

Galvanised steel pipes originally supplied water from the public mains to the house, and copper pipes supplied water to fittings in the house. PVC and polybutylene did not become available until the 1960s.

Where a public water supply was not available, such as in rural areas, rainwater was used. Roof rainwater collection systems did not generally feature a first flush system, and rainwater tanks were often poorly protected, sometimes resulting in poor water quality. Rainwater tanks were generally positioned at a height to allow a gravity-fed system to operate.

Local authority water supplies often came at a lower water pressure than today, and it was common to have a header tank on the roof to increase water pressure through gravity.

Back to top

Common problems and remedies

Low pressure hot water systems

Early installations were typically either gas califonts (geysers) or low pressure electric hot water systems with a header tank installed in the roof space (where there was sufficient height) or mounted on a timber platform on the roof to provide sufficient water pressure.

It is unlikely that an original gas califont or geyser system is still in use as they were designed to burn coal gas, which is no longer available.

If a low-pressure electric system is still in use, there may be insufficient pressure to run some modern bathroom fittings. When renovations are being carried out, the hot water system should be converted to a mains pressure system, of which there are numerous options available. The pipework and fittings should be checked for their ability to cope with the additional pressure and it may be necessary to replace them.

The low-pitch roof and parapets of art deco houses lend themselves to roof-mounted solar hot water systems, as they may be able to be fitted without altering the appearance of the house from the street, especially if they are mounted to the rear of the house (Figure 1). A system that uses a roof-mounted cylinder may require additional strengthening to the roof and/or walls. An engineer should be consulted.

Deteriorating pipework

Original plumbing pipes would have been copper and may still be in good condition.

However, if a bathroom or kitchen has been upgraded, it is likely that replumbing has also been carried out. During the late 1970s and early 1980s, a particular type of black plastic pipe was installed into new homes as well as retrofitted into existing homes. After a time the product was taken off from the market because there were numerous incidents of pipes bursting and causing considerable damage. If there is black plastic piping from a renovation dating from this period, it may need replacing.

Uninsulated hot water system

The 2015 BRANZ House Condition Survey, involving over 500 houses, found that two-thirds of hot water pipes were not insulated – this equates to over 1 million houses across New Zealand. Retrofitting insulation to hot water pipes where practicable is a good idea.

Overall, 79% of cylinders that pre-dated 2002 (34% of all cylinders) had no cylinder wrap. This equates to just under half a million houses. The government’s Energy Efficiency and Conservation Authority (EECA) recommends adding a thermal wrap around cylinders manufactured before 2002.

Back to top

Sanitary drainage

By the 1930s, public sewer systems were widespread throughout cities and towns around New Zealand.

Early sewer mains were terracotta or cast iron pipes, typically ranging in size from around 9” (225 mm) up to 15” (375 mm) in diameter. Original domestic drainage pipes were earthenware, galvanised mild steel or cast iron, typically 4” (100 mm) in diameter that connected to the public system where it existed. If there was no public sewer system, the drain would run to a septic tank system.

Very early stormwater and sewage drains were sometimes combined. In central Auckland today, there are still areas with combined systems, although council rules require separation if larger additions or alternations are being made.

It is likely that the original domestic sewer drains, either earthenware clay or cast iron pipes, that connected to the public sewer system are still in use. Unless they are in poor condition, such as displaying cracks or deteriorated joints, they will not require replacement.

Where there was no public sewer system available, the drainage would have been into a septic tank system. The condition of the septic tank system should be checked and if it is functioning satisfactorily, it can remain.

Back to top

Who can do what?

Relatively simple plumbing jobs such as connecting up a washing machine or replacing a tap can be done by competent householders, but there are rules around who can do other types of work. Sanitary plumbing – work that involves water supply pipes or waste pipes, traps, ventilation pipes or overflow pipes – must be done by a licensed plumber. You can find more details here.