Taumarunui Water Supply

Is my water treated?

Yes, water is treated at the Taumarunui Water Treatment Plant, located adjacent to the Whanganui River on Echolands Road, Matapuna. A figure is provided below.

Water treatment at the Taumarunui Water Treatment Plant consists of the following:

1. Treating Water Hardness Water hardness is caused mostly by the minerals calcium and magnesium and can cause scum rings on bathtubs and cooking vessels, or scale on industrial boilers, which decreases the boilers' efficiency. In Taumarunui the water is 'softened' by the addition of soda ash.
2. Powdered Activated Carbon (PAC) Dissolved organic material in the water can cause taste and odour problems. To remove organic compounds Powdered Activated Carbon (PAC) is added to the water supply. Organic particles attach themselves to the surface of the carbon which is then removed from the water supply by finer filtration.
3. Sediment Settling Small unwanted particles or solids, such as fine sand and dirt, are removed from the water by adding a coagulant which gathers the solids into a cluster, creating larger solids which quickly settle to the bottom. Clean water can be taken from the top. This process takes place in clarifiers (pictured below).

1. Finer Filtration Water is passed through layers of sand and gravel to further 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.
2. Ultra Violet (UV) irradiation An upgrade completed in 2016 saw the addition of ultra violet irradiation to the scheme. 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). Is is also effective against many protozoa.
3. Chlorination & pH Correction The water is dosed with low levels of chlorine to kill off contaminants (bugs) in the reservoirs and pipes. pH correction is required to ensure effective disinfection with chlorine.

Where is my water stored?

Treated water is stored in the Matapuna reservoir (10,500m3), located on a hill above the Water Treatment Plant. Water is distributed from the Matapuna reservoir to consumers, and also to reservoirs in Rangaroa, Manunui, Te Peka, and Sunshine, which provide a further 4,575m3 storage capacity.

Booster pumps within the supply system maintain pressure in the network and assist with the delivery of water to the outlying reservoirs.

Below is a picture of the storage reservoirs at Rangaroa.

Water monitoring

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

Our pipelines

The Taumarunui Water Supply Reticulation Network consists of around 68.2km of pipeline. Most pipes are 50-100mm in diameter and Asbestos Cement and Plastic (uPVC) are the main pipe materials. The average water main age is 40 years. Pipes are replaced when they are 'too old'. This is indicated by leaks, rust and pressure loss. Emphasis will be needed on replacing these pipes in the near future.

The following schematic shows flow through the water supply scheme.