The Westland District Council was today flying in an international expert to try to pinpoint the problem with the Hokitika town water supply.
Residents have been complaining of a variety of issues since Tuesday last week, including 'oily' or 'waxy' water and even wet hair left standing on end, imbued by a gel-like substance during showering.
One person last week recountied to the Hokitika Guardian how she was unable to rid her wet hair of the greasy residue following her morning shower, while her partner's hair was left sticking on end after a shower the same day.
Another resident contacted the Guardian concerned that a mineral compound aluminium hydroxide may have got into the water supply due to a faulty filter.
Aluminium hydroxide in freshly precipitated form manifests as a gel. It is commonly used in water treatment.
By yesterday the council had received 42 formal complaints in relation to water quality since July 18.
In a statement last night, the council confirmed that it used aluminium hydroxide in the Hokitika water treatment but it was unsure if that was the cause of the problem.
"Westland District Council can confirm that our water treatment process does normally involve aluminium hydroxide and that this is a coagulant that does bind or clump particles together," the council said in a statement.
"We can not rule out yet that aluminium hydroxide may be a factor in the reported water quality incidents, but this is by no means definitive at this stage."
It was today flying in a water treatment expert to Hokitika, familiar with the town water treatment plant mechanisms to conduct on-site investigations.
The council had also hired a West Coast water engineer on a short-term contract to assist the ongoing investigation.
Of 42 affected residents, 36 who had logged formal requests in relation to their water were able to be contacted by council staff yesterday.
"The majority have reported improvements in their water quality, including improvements in the taste and appearance of the water, decreases in 'greasiness,' and bath and dishwater once again forming bubbles and suds when combined with dishwashing or bubble bath liquid as it had prior to these reported quality issues."
The council said more data was needed before corrective action could be taken.
It was expecting to receive yesterday the results of water sampling on July 19, including samples from affected households. However, the results were still not to hand last night.
On Tuesday the council said it initially expected results in four days. It was expecting further sample results to be available early next week.
In the interim, council staff had been flushing hydrants around some affected areas of the town in order to remove any greasy residue from the lines, the statement said.
District assets and engineering manager David Inwood said on Tuesday the council had not altered its water treatment process recently.
"Reports of water appearing 'oily' or 'waxy' are not because of any chemical treatments that we have added to the water supply," Mr Inwood said then.
The council had experienced two water breaks last week which while unrelated, had led to additional aeration of the water. This left water appearing cloudy water, "compounding the initial situation".
Staff had already ruled out a number of concerns, including the presence of e.coli, he said.
- by Brendon McMahon of the Hokitika Guardian
