30 July 2013
Well shut down after discoloured water affects parts of Gore
The Gore District Council has stopped drawing water from one of its wells at Jacobstown after some Gore residents had to deal with discoloured water at the weekend.
North and West Gore residents were affected by the discolouration, which was caused by manganese in the water supply.
District assets general manager Paul Withers said the water for these parts of Gore comes from a relatively new well at Jacobstown. When the well was commissioned, about four years ago, there was no evidence of high manganese levels. However, the trace element has become prevalent over time.
No health risks
Mr Withers stressed there were no health risks from the manganese but acknowledged it was a major inconvenience for those who have had to put up with it.
When fabrics are washed in manganese-bearing water, dark brown or black stains are formed due to the oxidation of the manganese.
“I live in the affected area so know exactly how people feel.”
When manganese is drawn into the network it usually ends up accumulating on the bottom of the pipes. It is only when the water is stirred up, for example when there is a big draw on the urban supply, that it causes discolouration and affects the look and smell of the water coming out of peoples’ taps.
“Past experience has shown that by turning off the well and flushing the system, we minimise the potential for any more incidents such as the one on Sunday,” Mr Withers said.
This was a short term fix though. When water demand increases the Council will have to resume pumping from the well, he said.
Water Supply Strategy identifies options
Mr Withers said a Council working party has been investigating new sources of water over the last few years, which has placed water treatment investigations on hold.
The Water Supply Strategy, endorsed earlier this year by the Council, failed to identify viable alternative water sources but looks at various options for the water supply. These include leak detection, water capture and storage, and the rationalisation of water treatment plants.
Managing risks to water supply in plan
The Council has also completed a Public Health Risk Management Plan, which has been approved by the Ministry of Health. This identifies risks to the water supply and how these can be managed, including the level of water treatment required to meet national standards.
Mr Withers said with this important investigative work now in place, staff will be working on a strategy to raise water treatment quality to meet customer expectation and further reduce risk.
The best options for upgraded water treatment, how much it will cost and how it will be funded are likely to be part of the next Annual Plan and Long Term Plan processes.
“These are not decisions that can be rushed. We don’t want to spend a lot of money until we understand how everything fits together.”
If approved, work on an upgraded water treatment plant was still about three years away, if not more, Mr Withers said.
The Council was not the only local authority to experience problems with manganese. The frustrating aspect about the Jacobstown well was that there was no warning when it may appear, he said.
Further treatment of water from the well will be investigated or it may have to be abandoned, Mr Withers said.