Low flows on Makotuku leave sour taste in water


2015-11-13T14:46:00 Pacific/Auckland


The early taste of summer is leaving a sour taste in Raetihi’s tap water as unseasonal low flows on the Makotuku River are encouraging the growth of algae.

The recent taste and odour issues affecting Raetihi’s water supply is due to these naturally occurring growths that start to bloom in the township’s water source the Makotuku River during periods of low water flow and warm weather.

Ruapehu District Council Environmental Manager, Anne Marie Westcott, said that unfortunately this has become a yearly occurrence and council staff has already been fielding calls about it and it’s only November.

“This year as river levels have decreased we are finding the algae causing water quality issues across the catchment and as high up in the Makotuku River as Horopito,” she said.

“The important thing for all Raetihi residents on council supplied water to note is that despite any taste or odour the township’s tap drinking water is 100% safe and will not cause people to be ill.”

“Raetihi’s tap drinking water is treated, tested daily and is safe to drink and cook with.”

“Council’s water contractor Veolia Water takes water samples daily for testing from alternating points around the Raetihi reticulated water 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 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 tests on the water are for hydrocarbons and E.coli bacteria.”

“Hydrocarbons are measured for constantly via a sensor located at the Raetihi water supply intake on the Makotuku River while tests for E.coli bacteria are undertaken once a week and performed at an independent laboratory.”

Ms Westcott noted that 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.

“Council has recently been awarded a grant from the Ministry of Health to build a new water treatment plant for Raetihi which is fantastic news,” she said.

“We are currently in the process of putting together contract documents with the whole build expected to take around two years so unfortunately it’s not today’s solution.”

Ms Westcott said that in an effort to provide more transparency and education around issues affecting Raetihi’s water supply council was now publishing graphs of water flows on the Makotuku River as well as the results from the hydrocarbon sensor on its Facebook page www.facebook.com/ruapehudc and website www.ruapehudc.govt.nz

“People viewing the hydrocarbon sensor graph should note that the very low levels of hydrocarbons showing are due to naturally occurring sources from decaying vegetation in the river.”

“Of more real concern are the graphs for water flow in the Makotuku which show we have just been keeping our head above where water restrictions are automatically introduced,” she said.

“Households should introduce good water use practices and try and make every drop count.”

For more information see council's Water Services Notices webpage: http://goo.gl/dDWby6


Page reviewed: 13 Nov 2015 2:46pm