Napier City Council spending almost $4000 per month dealing with brown water complaints

Napier City Council is spending almost $4000 per month, on average, flushing out water pipes due to complaints about discoloured water.

Residents have complained about the issue since the water supply was chlorinated in May of 2017 following the Havelock North campylobacter outbreak.

Figures obtained under the Official Information Act show the average cost per month of flushing out water pipes has been $3875 in the 19 months between May of 2017 and November last year. The total cost to council over that time period was $73,630.

NCC Infrastructure Manager Jon Kingsford told 1 NEWS in December that complaints about water discolouration are "rare", but the figures show, on average, about 60 complaints are received each month relating to discoloured water - about two per day.

The highest number of complaints received in a month was 185, in December of 2017, while the lowest number was 16, received in March last year.

Napier City Council spokesperson Cheree Ball said the council does not employ external contractors to undertake the flushing work, instead using its own City Services team.

"It should be noted that the service requests may not directly correlate to the number of pipe flushings, as there can be multiple calls from ratepayers about the same event which is already being attended to," she said.

WHAT'S CAUSING THE BROWN WATER?

NCC says the discolouration is the result of "harmless biofilm" being washed out of the pipes during routine maintenance.

The council has denied the issue has been made worse or more frequent by chlorination, but many residents spoken to by 1 NEWS say the problem never existed before the water supply was chlorinated.

"Biofilm is a collection of organic and inorganic living and dead material attached to the pipes' surfaces," Mr Kingsford said.

"Bacteria as [biofilm] is harmless (non-pathogenic species), however they accumulate different elements including iron, manganese and their oxides from the water during their life cycle.

"When the bacteria die off, inorganic remains stay there and build up over years – this is what can be found in the sediment after mains cleaning activities or flushing."

Christchurch City Council, which in March chlorinated its water supply for similar reasons to Napier, says on its website that "chlorine is a powerful oxidising agent".

"As it travels through the system, it will react with any organic matter, such as slime build-up in the pipes," CCC says.

"It might also react with iron in the old cast iron mains and it will react with any other organic material it comes across."

IS THE BROWN WATER SAFE TO DRINK?

NCC's advice for people bothered by the discolouration is to run the cold tap until their water clears, to install a filter, or to call the council if the water won't clear.

NCC maintained the discoloured water was purely an aesthetic issue and never expressly warned residents not to drink it.

However, test results obtained by 1 NEWS last year showed extremely elevated levels of manganese in the discoloured water, leading some experts to express concern.

Excessive manganese consumption has been linked to serious health issues, including learning disabilities and other health issues for infants, the elderly, and those with certain conditions.

After 1 NEWS ran a story about the results, the council continued to maintain it was safe to drink the water, but also updated their website, saying that "to have any health effects from drinking this water, you would need to ingest it frequently over a long period of time".

They also included advice from Dr Belinda Cridge, Programme Director of University of Otago's Pharmacology and Toxicology Department, who recommended a precautionary approach for vulnerable groups who may drink the water.

The groups include infants, pregnant women and the elderly.

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