In this section

  • Water Quality

    Information about our water quality and our means of compliance and advice on protecting our water supply

Schemes under chlorination

Here are the schemes that are chlorinated:

  • Upper Selwyn Huts Water Supply
  • Dalethorpe Water Supply
  • Hororata - Acheron (Hororata) Water Supply
  • Hororata - Acheron (Acheron) Water Supply
  • Sheffield/Waddington Water Supply
  • Springfield Water Supply
  • Castle Hill Water Supply
  • Hartleys Road (Malvern Hills) Water Supply
  • Arthurs Pass Water Supply

Please refer to our Water Schemes map or to your Rates Information to check which scheme you are in.

Temporary Chlorination

If you are looking for schemes under temporary chlorination please see the urgent notices page

Why we are adding chlorine to some water supplies

  • Chlorine is used as a preventative measure against contamination.
  • UV (ultra violet light) treats the water where it enters our supply network. It is very effective as long as the water is not turbid (discoloured). UV treatment does not treat the water once it is in our reservoirs and pipes.

The amount of chlorine in water

  • Typically we will use a dose of 0.4mg to 1.0 of chlorine for every litre of water. This will give a residual dose of 0.2mg per litre in what comes through your taps.

Tips to removing the chlorine

  • You can install an under-bench filter or fill a jug of water and leave it on the bench or in your fridge overnight. The chlorine will dissipate naturally over a few hours.
  • Chlorine and any associated by-products can be removed by using a granulated, activated carbon (GAC) filter. These are available from hardware supplies stores and water filter companies.
  • What to do if you don’t want to shower or wash your clothes in chlorinated water: You can buy at your own cost a carbon filter that attaches to your water supply where it enters your property. It will remove all the chlorine from the water to your home.
  • The use of filters will mitigate any risks for those on dialysis. This can be arranged by the Canterbury District Health Board.

Animals and chlorination

  • If you have fish in outside ponds you will need to either turn down in-coming water to an absolute trickle (this dilutes the chlorine level to a safe amount for your fish), or fill up drums of water and let them sit for at least 24 hours before using (the UV of the sun evaporates chlorine).
  • For fish tanks or bowls inside, fill up a container of water and let it sit for at least 24 hours and then only replace a third of the water at a time. If you’re still worried, you can buy de-chlorinating kits (sodium thiosulfate) at pet supplies stores.

History and safety of chlorine

  • Chlorine has been used safely all over the world for around 120 years. It keeps millions of people all round the world – including most of New Zealand – safe from waterborne disease.
  • The amount of chlorine dosed into the water supply is carefully managed to ensure levels of chlorine in the water people drink are absolutely minimised.