Waiuku residents are disputing the cleanliness and drinkability of their water.
Priyan Perea, Watercare’s water supply operations manager has responded to questions surrounding issues raised about the source, the quality, discolouration, limescale buildup and treatment of the Waiuku water .
Priyan said Waiuku’s water is sourced from three bores that take the water from the Waiuku Kawa Aquifer. The bores are located at three different locations in Waiuku.
As to the limescale buildups, he said this occurs because of naturally occurring minerals.
“Like many groundwater sources around the world, the water contains naturally elevated levels of dissolved minerals from surrounding rocks: sodium, calcium, magnesium, potassium, chloride and bicarbonate. They are not harmful and give Waiuku water a distinct taste, very different to that of rain water,” he said, adding that health experts have indicated the minerals calcium and magnesium are important for maintaining human health.
The levels are well within applicable New Zealand and international guidance and standards.
Priyan said prior to the integration of Auckland’s Councils in 2010, Waiuku’s water supply system was ‘E’ graded, with no treatment processes in place, and frequent instances of source contamination.
“Since 2010, when Watercare took over responsibility of Auckland’s water supply system, more than $2 million has been invested in upgrading Waiuku’s water supply,” Priyan said. “The water now undergoes an extensive treatment process at the Waiuku Water Treatment Plant, including being dosed with chlorine, undergoing filtration and ultra violet disinfection (which inactivates bacteria and protozoa,”— which single celled organisms that can cause infections.
Now, Watercare says Waiuku’s water is independently assessed and received an A-a grading (very high quality), and meets all the requirements of Drinking water safety New Zealand.
Priyan said the treatment process is designed to remove iron and manganese from the water.
“Any discolouration will be due to historic scaling in the network, which may be dislodged from time to time during periods of high demand,” he said.
He suggests that residents check with dishwasher and washing machine manufacturers first, before adding any products to try to overcome this, (for example vinegar), and are advised to check hot water cylinders and kettles regularly to ensure elements for signs of scaling. The water is called hard water due to the high mineral content, and many countries including Australia and London, and 85 percent of Americans have ‘hard water’.
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Calcium and magnesium
Waiuku’s water supply contains calcium and magnesium at a range of 65 – 30mg/L and 20 – 10 mg/L respectively. These levels are well within applicable New Zealand and international guidance and standards says Watercare.
Iron and manganese
Resident concentrations of iron and manganese in Waiuku’s untreated bore water is between 1.0 mg/L and 0.6 mg/L, which is above their guideline values in Drinking water standards New Zealand (DWSNZ). The treatment process lowers the concentration of iron and manganese to a maximum of 0.007 mg/L and 0.004 mg/L. These concentrations are well below the guideline values in DWSNZ says Watercare.