How we manage water

How we manage our water demand

  • High growth in the eastern urban townships including Rolleston, Lincoln, West Melton and Prebbleton, is driving the need for more public drinking water from these townships’ sources - both at existing and new sites.
  • All current township water restrictions are notified on this web page and our Facebook page. You can also sign up to receive urgent water notices by text and email here.

We have two types of water supply in the district: on-demand (unrestricted/metered) and restricted supply.

If the network in your area has reached full capacity and no new connections are available, you may need to consider a private water supply.

Private water supplies

Not all properties in Selwyn are connected to Selwyn Water’s reticulated (public) drinking water supply. Many households and businesses rely on alternative water sources, including:

  • A private bore (well) or roof‑collected rainwater stored in tanks.
  • Privately owned reticulated supplies, where a group of homes share a privately managed network. Older private systems may carry higher risks of pipe breaks or contamination.
  • Small community supplies, such as those operated by schools, campgrounds or other small facilities.
  • Public community supplies and water race water, depending on the area and available infrastructure.

Your responsibilities 

If your drinking water comes from a private source, you are responsible for ensuring it is safe to drink. This includes:

  • Knowing where your water source is and ensuring it is well maintained.
  • Regularly testing your private supply. Environment Canterbury recommends routine testing for pathogens and nitrates, plus a one‑off test for heavy metals and organic chemicals.
  • Following safe drinking water guidance for private supplies.
  • Seeking advice early if you plan changes to your property or water system.

Water storage tanks

Many rural properties need water storage tanks for household use and fire‑fighting requirements. To keep tank water safe:

  • Ensure tanks are sealed to prevent birds, animals, and insects from entering.
  • Repair cracks, gaps, and unsealed lids.
  • Screen breather holes to prevent insect entry.
  • Follow recommended steps for disinfecting tanks when needed.

Restricted water supplies

Some properties in Selwyn receive water through a restricted supply, which provides a set amount of water each day rather than on-demand flow. These supplies must have on‑site tank storage and pumps and require customers to keep an eye on storage levels and maintain their private plumbing to ensure water is always available.

How restricted supply works 

If you live in a restricted water scheme area, and are connected to the Selwyn Water network, you must have:

  • A suitable water tank storage
  • A pump to move water from your tank into the home
  • Enough water tank storage to meet the minimum requirement for your area (shown in LIMs and PIMs)

We recommend installing a water tank large enough to hold at least three days of water. More storage improves resilience during maintenance or outages and helps your system recover more quickly.

Restricted supplies include a restrictor which is installed and maintained by Selwyn Water. Pipes and fittings on Selwyn Water’s side are shown in blue in standard diagrams; pipes on the customer side are shown in pink and must be installed and maintained by the property owner.

 

How much water you receive 

Restricted water supplies deliver water in fixed daily units:

1 water unit = 1,000 litres over 24 hours

Water is delivered to your private storage tank via a restrictor that controls flow. You receive the same daily amount regardless of demand.

Your responsibilities 

Once the water passes the point of supply, responsibility shifts to the property owner. You are responsible for:

  • Monitoring the water level in your tank
  • Ensuring your tank is large enough to avoid running out if you exceed your daily allowance
  • Paying for a private tanker refill if your tank runs dry and you need urgent water
  • Keeping the area around your equipment clear and accessible
  • Not allowing others to take water from your point of supply without approval
  • Checking for underground pipes before digging or planting

If you damage Selwyn Water-owned pipes during excavation, you will be liable for repair costs.

Our responsibilities 

Selwyn Water is responsible for:

  • Supplying, installing and maintaining the restrictor
  • Maintaining the lateral pipe from the water main to the restrictor
  • Approving and inspecting any new laterals built at the owner’s cost
  • Testing your restrictor if you believe it is not delivering the correct amount of water

To request a restrictor inspection, please contact us. If the restrictor is found to be faulty, you will not be charged for the inspection.

Applying for a change to your water units 

If you need to request an increase or decrease in your water units, please submit an online application form.

While we will assess your request, approval cannot be guaranteed. Any alteration that can be supported will be permanent. A request to increase water units can only be made up to the maximum allocation allowed for the water supply scheme you are connected to. In most cases, a water‑modelling assessment may be required to confirm available capacity within the scheme.

Annual tank maintenance 

All customers on a restricted water supply must clean and disinfect their water storage tanks at least once a year.

Guidance on how to clean and disinfect your tank is available on Health Ed.