NELSON BUILDING REPORTS

Dux Qest — leaky pipes?

60 years ago all New Zealand houses used galvanised steel pipes for the water supply and distribution.

Water and steel don’t mix well, due to rusting. The flow of water containing impurities is abrasive and the chemicals in water attack the inside galvanising of the pipe.

Over time, although the exterior of the pipe looks okay, the inside of a pipe can start to corrode. The corrosion restricts water flow, and eventually blocks the flow completely.

So by the 1960s most plumbers moved to using copper. Copper does not corrode in the same way, it is very stable in most domestic situations. But copper used in the piping became expensive.

In the 1970s plastics were experimented with. One new material was polybutylene. One manufacturer, Dux, came up with a product known as Dux Qest. (That is the correct spelling by the way. It is not spelt Quest.)

Dux Qest was extensively used in Nelson in a period from 1979 to 1991, both for new houses and for replacing old galvanised pipes in existing houses, or renovations. Many houses in Nelson built or modified from 1979 to 1991 have potentially leaky water pipes.

Dux Qest has proved to be severely faulty.

With this early formulation of polybutylene, Dux Qest, the chlorine in the town water supply reacts with the plastic, causing it to erode, and/or become brittle. Eventually it breaks down and leaks. When those pipes leak they can be like a tap, full blast, except inside your walls.

Leaky pipes can cause a lot of damage. Hundreds of litres of water can be discharged inside the house before the boundary water tap is turned off.

Then the Dux Qest pipes need to be replaced. That means removing much of the wall linings in bathrooms and the kitchen. Access to some pipes can be difficult, particularly in two storey houses.

If you replace some of the wall linings, it can become all of them. Then you might as well replace the ageing fittings too.

Replacing a leaking pipe can lead to a full bathroom renovation, which can end up costing tens of thousands of dollars. This cost may not be covered by your house insurance policy, particularly if it is a known problem.

So, leaking pipes are expensive to remedy. It can become very expensive.

It’s better to know about this issue before you buy a house and factor any costs into your purchase price.