Water heating – leaking pipes

Leaking pipes may not be visible but may show as dampness on floors or walls or mould growth on surfaces. Locating and repairing the leak may involve the removal of internal linings or claddings.

Causes

Faulty connections

Insufficient number of pipe supports causing undue vibration in pipes 

Water too hot for polybutylene pipes

Water pressure too high for polybutylene pipes

Pinhole corrosion in copper pipes due to carbon left in pipes after manufacture 

Water with a high pH damaging copper pipes

Corroded galvanised pipe

Rodents chewing PVC pipes

A nail or screw has pierced the pipe

Listed under: metal, plastic, polyvinyl chloride (PVC), water heating, plumbing, pipes, Services, durability, corrosion

Cause

Faulty connections

Repair

  • contact a registered plumber to repair/replace faulty pipe connections. (Work on replacing hot water pipes or plumbing connections in a house falls into the category of ‘sanitary plumbing’ and DIY is not permitted.) 

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Cause

Insufficient number of pipe supports causing undue vibration in pipes 

Repair

  • increase the number of fixing clips/pipe supports

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Cause

Water too hot for polybutylene pipes

Repair

  • reduce the water temperature. If a storage cylinder is used, the water must be heated to over 60°C to prevent the growth of Legionella bacteria. The water must then be tempered to reduce the temperature before it is delivered to outlets. The delivery temperature of hot water to sanitary fixtures used for personal hygiene in housing such as baths, showers and hand basins must be no more than 50°C. (This was reduced from 55°C when G12/AS1 was amended in November 2023, with a 12-month transition period


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Cause

Water pressure too high for polybutylene pipes

Repair

  • contact a registered plumber to fit a pressure-reducing valve

  • if you want to retain high water pressure (to operate appliances designed for this, for example), ask a registered plumber to replace the pipes with pipes of a more appropriate material

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Cause

Pinhole corrosion in copper pipes due to carbon left in pipes after manufacture 

Repair

  • contact a registered plumber to repair/replace leaking pipes

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Cause

Water with a high pH damaging copper pipes

Repair

  • talk to a local registered plumber about options for modifying pH levels (i.e. reducing the acidity) of water entering the house

  • engage a registered plumber to replace damaged/corroded pipes

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Cause

Corroded galvanised pipe

Repair

  • old galvanised pipes that are likely to be at or near the end of their serviceable life should be replaced by a registered plumber with either:

  • polybutylene or polypropylene, the most common choice

  • copper piping. Copper is long-lasting, easy to work and generally has good corrosion resistance. In areas where water is more acidic than usual, however, polybutylene or polypropylene pipes may be preferable

  • where cold water pipes are installed outside of the building’s thermal envelope they should be insulated if frosts/freezing temperatures are possible. All hot water pipes should be insulated. Use purpose-made, preformed insulation a minimum 13 mm thick

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Cause

Rodents chewing PVC pipes

Repair

  • engage a registered plumber to replace damaged pipes

  • contact a pest exterminator to deal with the rodents. Look for an exterminator who is a member of the Pest Management Association of New Zealand

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Cause

A nail or screw has pierced the pipe

Repair

  • engage a registered plumber to replace the damaged pipe

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