Raetihi Tap Water Taste & Odour Issues Caused By Natural Alg
Raetihi Tap Water Taste & Odour Issues Caused By Natural Algae
Taste and odour issues with Raetihi’s reticulated (tap) water is due to naturally occurring growths of bacteria and algae in the Makara Stream the township’s current water source.
Ruapehu District Council Environmental Manager, Anne Marie Westcott, said that despite any taste or odour Raetihi township’s reticulated (tap) drinking water is safe to drink and will not cause people to be ill.
“Raetihi’s reticulated drinking water is treated, tested daily and is safe to drink,” she said.
“Council’s water contractor Veolia Water takes water samples daily for testing from alternating points around the Raetihi reticulated network as well as a weekly test for E.coli bacteria.”
“The daily water samples are tested for four key factors being; free available chlorine (FAC) which is a measure of the chlorine left in the water after treatment, the pH level which is a measure of alkalinity and acidity, water temperature which affects the pH level and turbidity which is a measure of organic material in the water.”
“The other significant test on the water is for E.coli bacteria which is undertaken once a week and performed at an independent laboratory.”
Ms Westcott said that E.coli is an indicator species of bacteria that live in warm blooded animals and can cause diarrhea, dehydration and vomiting in humans.
“The E.coli test requires the laboratory to see if a culture grows in the water sample which takes 48 hours so ‘instant’ results are not possible.”
Ms Westcott noted that there has been no positive E.coli found in the Raetihi water treatment plant of the reticulated network since 2010.
“The natural growths of bacteria and algae are more prevalent at this time of year when the water flows are lower and are found in many Ruapehu waterways including the Makotuku River which was the source of Raetihi’s water prior to the diesel contamination and the Whanganui River that supplies Taumarunui,” she said.
“The ecology of the individual waterway will affect the taste, odour and clarity of the water with the smaller size and slightly different characteristics of the Makara tending to amplify any effects.”
“With the Makara Stream being much smaller than the Makotuku River it has a smaller water flow and along with travelling through more open land it is more susceptible to these growths.”
“Removing taste and odour is not a simple process and requires a full treatment system which even then may not always remove all of the ‘taint’ in the water.”
Ms Westcott added that Veolia has indicated that the fine air bubbles which make tap water look ‘milky’ that got into the treatment system due to the failure of the raw water pipe last week are now dissipating out of the pipes.