National Park Water Supply

​The National Park Water Supply system provides potable water to approximately 316 properties within the National Park community.

Where does my water come from?

Water for the National Park water supply is taken from the Mangahuia Stream, located in the Tongariro National Park off State Highway 47.

Is my water treated?

Yes. Raw water is gravity supplied by pipe to the nearby National Park Water Treatment Plant where it undergoes the following processes:

  1. Rapid Sand Filtration
    Water is passed through layers of sand and gravel to remove impurities. Small water molecules pass through the holes between sand and gravel pieces and clean water is collected in a drain at the bottom. Unwanted solids get stuck in the holes, and are thus retained in the sand and gravel medium. This medium is washed from time to time to remove the unwanted solids. The water is also monitored for Turbidity (cloudiness) which is caused by small solids in the water that have not settled out but have remained suspended in the water. These solids can interfere with chlorination and ultra violet treatment of the water as bacteria and viruses can be shielded by the solid particles.
  2. Chlorination
    The water is dosed with  chlorine to kill off contaminants (bugs) in the reservoirs and pipes.  The chlorine levels are monitored 24 hours a day, seven days a week, by online monitoring which allows any changes to the dose to be alerted to the operator in real time.

  3. Ultra Violet (UV) Treatment
    Water is further treated by exposure to Ultra Violet light. This kills any bacteria and viruses remaining in the water supply by destroying their genetic core (DNA). It is also effective against many protozoa.


Where is my water stored?

Treated water is stored within the National Park reservoir (500m3), on State Highway 47 and pictured below. 


Water Monitoring

Online monitoring through Supervisory Control and Data Acquisition (SCADA) provides information about the water treatment, such as chlorine and turbidity. This system checks that water parameters stay within set values for 24 hours every day and will alert the Plant Operator if anything changes.


Our pipelines

Treated water is  piped from the storage reservoir to National Park township. The National Park Water Supply reticulation network consists of 15km pipeline.  Most pipes are 100mm or 150mm in diameter and are made of plastic (uPVC).  The entire system is gravity fed.

Flow through the scheme is shown in the figure below.


Page reviewed: 27 Apr 2016 7:01pm