Rust-coloured water

Causes

Corrosion of old galvanised pipes

Listed under: plumbing, pipes, Services, durability, corrosion

Cause

Corrosion of old galvanised pipes

Repair

  • a short-term solution is to run the tap for a few seconds first thing each morning. The Ministry of Health recommends flushing a mugful of water from the tap each morning to remove any metals that may have dissolved

  • old galvanised pipes that are likely to be at or near the end of their serviceable life should be replaced by a registered plumber. (Replacing the water supply pipes in a house falls into the category of ‘sanitary plumbing’ and DIY is not permitted.) Replacing the pipes may involve the removal and reinstatement of internal linings and/or wall claddings.

  • polybutylene or polypropylene piping is the most common choice

  • copper piping is another option. 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 to minimise heat loss. Use purpose-made, preformed insulation a minimum 13 mm thick

  • Make sure piping is installed in a way that reduces the risk of ‘water hammer’ – a nuisance knocking sound that can occur when fast-moving water in a high-pressure system is suddenly stopped. To reduce the likelihood of water hammer:

    • clip pipes with rubber insulated clips or clip over the pipe insulation

    • fix pipework rigidly to prevent movement

    • provide relief bends or flexible sections of pipe to absorb shock

    • fit grommets or cushioned packers where pipes pass through structural members.

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