What is a restricted water supply?

Unlike most urban water supplies, where water is available on demand directly from the network whenever you turn on a tap, restricted water supplies deliver a set volume of water to your property each day.

Restricted supplies are used on some rural, rural-residential and urban fringe water schemes where available water resources and infrastructure capacity need to be carefully managed. They are also commonly used to service properties on larger land sizes, where water demand is typically higher and metered, on-demand use could place significant pressure on the network and reduce the reliability of supply for other connected properties.

Water is delivered continuously by trickle feed throughout the day through a flow restrictor, which controls the rate at which water enters your private storage tank.

Why some properties have a restricted supply while others nearby have a water meter

The type of water connection provided to a property depends on several factors, including:

• The water scheme it is connected to
• Available infrastructure capacity, for example the size of the network pipes, pressure and distance to the treatment plant
• Property size
• Anticipated demand
• The standards and requirements that applied when the property was developed

In some areas, there is a mix of metered and restricted connections, often reflecting differences in land size and demand. In rural, rural-residential and urban fringe areas, restricted supplies are commonly used to help manage available water resources and ensure a reliable supply can be shared fairly among connected properties.

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 bright blue and must be installed and maintained by the property owner.

Water is allocated in units

One water unit provides 1,000 litres of water over a 24-hour period.

The number of units allocated to your property determines how much water is delivered each day.

How water units are allocated

Water connection requirements, including the type of connection and, where applicable, the number of water units allocated to a property, are typically determined during the planning and consenting process.

Allocations are based on a range of factors, including:

• Property size
• Intended land use
• Anticipated water demand
• Available scheme capacity
• Engineering requirements at the time of development

If you're unsure why your property has a particular allocation, your Resource Consent, Land Information Memorandum (LIM) report or other property records may provide information about the servicing requirements that applied when the property was developed.

Your water allocation represents a share of the scheme

For properties on a restricted water supply, allocated water units represent a share of the scheme's available capacity that has been reserved for that property.

Even if you don't use your full daily allocation, the infrastructure and network capacity needed to provide that level of service must still be available and maintained. This is why restricted water charges are based on allocated water units rather than the amount of water used on any given day.

Fully restricted schemes

Some Selwyn water schemes, including Hororātā, Dalethorpe and Acheron, are fully restricted and fully allocated, meaning all available capacity within the scheme has already been assigned to connected properties.

These schemes are supplied by surface water sources, where water availability can be more vulnerable to seasonal and environmental conditions. In these schemes, water allocations help ensure available supply can be shared fairly and reliably while supporting the long-term sustainability of the water source.

In fully allocated schemes, if you choose to reduce your allocation, it may not be possible to increase it again later. Any surrendered water units may be reallocated by Selwyn Water to other properties waiting for capacity.

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

• Not tampering with or removing the restrictor (this is an offence under the Selwyn District Council’s Water Supply Bylaw and may result in repair costs or prosecution)

• Checking for underground pipes before digging or planting. If you damage Selwyn Water-owned pipes during excavation, you will be liable for repair costs.