In this section

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

We want to make sure that our community has safe drinking water. The Health Act makes the Council responsible for providing a safe and wholesome drinking water supply and to do everything practicable to meet the NZ Drinking Water Standards.

Report an issue with your water

Use our customer enquiry form or call us directly to report a perceived issue with the quality or quantity of your drinking water when connected to our network.

How we protect our water supplies


  • Selwyn District Council takes water samples to monitor microbial contents (regular bacterial testing) of the source water, treated water and from reticulation according to the Drinking Water Standards for New Zealand requirements.
  • Currently Selwyn District Council tests all water sources for chemical determinands on an annual basis. Please refer to Annual Chemical Test Results.
  • Our water quality monitoring is governed in compliance with Drinking-water Standards for New Zealand
  • Our Water Supply Bylaw 2008 applies to water supplies under the care, control and management of, or water provided by, the Selwyn District Council, except for water supplies subject to the Selwyn District Council Water Race Bylaw.


  • Treatment methods used in various supplies include secure ground water, Ultraviolet (UV) disinfection, selective abstraction and filtration, while chlorination is currently used on seven suppliers.
  • Chlorine is used as a preventative measure against contamination. Note that over 80% of the country is being supplied with chlorinated water.
  • UV (ultra violet light) disinfection treats the water where it enters our supply network. UV treatment does not treat the water once it is in our reservoirs and pipes.
  • There is always the potential for contaminants to get into the water reticulation system, for example through cracks in the reservoir, broken pipes – tree roots growing through pipes are a potential problem, as are unlawful connections from households where people have done their own plumbing.


Water Treatment / Barriers

Turbidity Monitoring


Ultra Violet Light

Permanent Chlorination

Secure GW

Arthur's Pass 
Castle Hill   
Lake Coleridge  
Malvern Hills Hartleys 
Malvern Hills Dalethorpe 
Selwyn Rural – Acheron   
Selwyn Rural - Hororātā 
Sheffield / Waddington 
Deep Groundwater
West Melton 
Jowers Road   
Raven Drive  
Rakaia Huts 
Tai Tapu  
Te Pirita  
Upper Selwyn Huts  
Greater West Melton  

Send your enquiries to our services using the customer enquiry form

How you can help

Get your backflow protection tested

  • Our backflow prevention policy sets out the backflow prevention requirements for new and existing properties in the district.
  • Backflow prevention device installed at high, and medium hazard properties must be tested annually by an approved backflow Technician or Independently Qualified Person (IQP) at the property owners' expense.
  • All privately managed backflow devices within the boundary should be included in the property’s compliance schedule and be maintained fully functional.

Flush your taps

  • Traces of metals – in particular lead – are of concern because over time they pose a potential health risk, especially if consumed from childhood. The whole phenomenon is technically known as ‘Plumbosolvency’.
  • The Ministry of Health therefore recommends that people do not drink the first mugful of water if their tap has not been used for several hours overnight, or after long absence from your property. Instead, people should run the tap for a second or so, which will quickly flush-away any water that has become contaminated with lead or any other metals from the plumbing fittings.
  • Additional details on this issue can be sourced from the Ministry of Health website – or the Plumbosolvency Q & A Sheet [PDF, 34 KB]

Disinfect your water storage tank

Risk Assessment of our water supplies

  • Following consultation on the 2018-2028 Long-Term Plan, the Council voted to develop a risk-based assessment for determining which of Selwyn’s 30 water supplies should be chlorinated. We engaged BECA consultants to develop the assessment, and representatives from the Council, Sicon (the water supply operators), Food and Health Standards (Environmental Health Officer) and Drinking Water Assessor (Community & Public Health) also contributed.
  • The assessment looked at the source, treatment, reticulation and end users of each scheme, and considered a number of factors such as well depth, treatment, turbidity, risk of flooding, stock exclusion, population including vulnerable populations, growth in number of connections, condition of pipes, and water pressure. Each water supply has been ranked from Priority 1 (highest risk) to Priority 5 (lowest risk). Chlorination has been recommended for supplies ranked Priority 1, along with some Priority 2.Read the full report on Risk assessment of water supplies  [PDF, 2555 KB]

Useful links