Why chlorinate? | Common questions | Community suppliesFurther reading | Contact QLDC

On the back of the Havelock North water contamination crisis in 2016 and after advice from Public Health South, Queenstown Lakes District Council has proposed to permanently chlorinate all Council provided water supplies across the district. This has been consulted on as part of the Annual Plan 2017/18

$500,000 has been allocated in the 2017-18 budget to chlorinate the water supplies for Arrowtown, Arthur’s Point, Glenorchy, Hawea and Luggate on a permanent basis. Providing budget for chlorination does not pre-determine the outcome of the consultation; it simply ensures that the funds are available to chlorinate if that is what the Council decides following consultation.

Wanaka and Queenstown’s water supplies are already chlorinated. 

Why chlorinate?

Supplying drinking water that is safe and clean is one of QLDC's core responsibilities. There is both the expectation and legal requirement that the water for residents and visitors alike is safe to drink. 

QLDC is obligated to learn from the Havelock North experience. An event of that magnitude in the Queenstown Lakes District would be very damaging on a local level, in terms of the effects to residents, but also seriously damaging to the region’s tourism sector. 

Drinking from an untreated water supply is much like driving without a seatbelt. While you may be safe for the majority of the time, when something adverse happens you are completely unprotected. Chlorine acts in the same way as a seatbelt – it protects those drinking from the supply from unexpected contamination events. Additional safety features are needed to protect against all possible infections, for example chlorine does not kill cryptosporidium.


Common questions

Why does QLDC want to add chlorine to the water?

We want to make sure that our families, friends and visitors don’t get sick when they drink our water. The Health Act makes QLDC responsible for providing a safe and wholesome drinking water supply and to do everything practicable to meet the NZ Drinking Water Standards.
UV treatment is very effective in killing bacteria and pathogens when water enters our treatment system. What it can’t do is continue to treat the water once it is in the reticulation network (our reservoirs, pumps and pipes). Chlorine disinfects the water all the way from the intake point to your taps. It also kills small bugs that can get through filtrations systems, such as bacteria and viruses that can’t be physically removed from water.

We already have UV treatment so why do we need chlorine too?

UV (ultra violet light) treats the water where it enters our supply network. It is very effective as long as the water is not turbid (discoloured). UV treatment does not treat the water once it is in our reservoirs and pipes.

There is always the potential for contaminants to get into the water reticulation system, for example through cracks in the reservoir, broken pipes – tree roots growing through pipes are a common problem, as are unlawful connections from households where people do their own plumbing.

How much chlorine will be used?

As little as possible to keep your water safe. Typically we will use a dose of 0.8mg of chlorine for every litre of water. This will give a residual dose of 0.5mg per litre in what comes through your taps.

What happened in Havelock North can’t happen here, can it?

It can, and it already has.

In 1984 before Queenstown’s water was chlorinated, about 3500 people in Queenstown became ill with gastroenteritis after a blocked sewer overflowed into Lake Wakatipu near the water supply intake.

In 2012 there was an outbreak of norovirus at Cardrona where 53 people reported being ill with diarrhoea, vomiting and nausea from contaminated water.

QLDC has regularly had to issue “boil water” notices for local communities because testing has shown E.coli in the water.

I’ve heard that chlorine is unsafe – is that true?

No. Chlorine has been used safely all over the world for around 120 years. It keeps millions of people all round the world – including most of New Zealand – safe from waterborne illness.

I hate the taste of chlorine – what can I do?

You have choices.

  • Fill a jug of water and leave it on the bench or in your fridge overnight. The chlorine will dissipate naturally over a few hours.
  • Install an under-bench filter

I don’t want to shower or wash my clothes in chlorinated water – what can I do?

You can buy a carbon filter that attaches to your water supply where it enters your property. It will remove all the chlorine from the water to your home. Examples include, or

Why are we proposing to chlorinate the water supplies in Arrowtown, Arthur’s Point, Glenorchy and Hawea?

From Chief Executive Mike Theelen


  • The law requires the Council to take all reasonable steps to protect drinking water and to meet NZ Drinking water standards. The law does not specify that water has to be chlorinated per se. Chlorination is our treatment of choice. It is cost-effective, reliable and easily implemented to substantially raise the level of protection of our water supply. Chlorine is already used to treat the water supply in Wanaka and Queenstown. It’s been commonly used internationally for over 120 years.

  • We have allocated budget in the 2017-18 Annual Plan to begin permanent chlorination in Arrowtown, Arthur’s Point, Glenorchy, Hawea and Luggate. That is why we are consulting the community.

  • It is open to people to demonstrate alternative means by which we could meet the Drinking Water Standards and provide a safe, secure water supply. These would have to be proven to be as effective and affordable as chlorine.

  • There are severe legal risk and possible penalties for the Council if we fail to take reasonable steps.

  • We are no less liable today than the Council has been for many years. QLDC has not acted consistently to date. Previous Councils and management have chosen not to provide a higher standard of water treatment despite this being on our water management plans for some time. Council has now allocated funding to implement chlorination as the preferred method of treatment forthwith, to put all public supplies on an even footing.

  • We emergency chlorinated Arrowtown and Hawea over summer, as they were assessed as being at highest risk. Glenorchy, Arthur’s Point and Luggate were not chlorinated. That action reflected the political decision to introduce emergency chlorination over the summer months and a commitment not to introduce chlorination by stealth.

  • It is foreseeable that the review currently underway as a result of the Havelock Nth incident will result in some form of mandatory control, or possibly the removal of this responsibility from Council. We can’t second guess that. We have raised the level of testing on the reticulation network for Hawea as an additional measure since finishing the prophylactic summer chlorination programme. This is a precautionary step in recognition of the continuing risk in this community in particular, given the amount of development in the area (which heightens the chance for incursion). What also have the ability to quickly introduce chlorination back into the Hawea supply should a decision be made or a positive E-coli test be returned.

  • Ultimately the Council has the right to decide, so there is an opportunity for Council to make a political decision.

  • We also need to be mindful that adding Chlorination and UV treatment will not get us to meet Drinking water standards, which requires ongoing work.

  • The consultation underway will allow anyone in the community to make a submission. We would expect that the community actively wants to improve the security of supply and therefore the council remains open to individuals offering alternative solutions that would meet the same or better level of protection.

  • If the Council chose a more expensive alternative method of treatment to satisfy a community’s preferences, it would have to consider where the costs of that choice should fall. Chlorination does offer, in staff opinion, the most cost effective system. That is why it is the preferred and implemented method of creating safer drinking water. The commitment to consult recognises that some communities in the district have strong views and this provides an opportunity for those to be aired and considered by Council.

  • While the advice of the specialists is that chlorine is very effective, there always remain to opportunity for alternative methods to be implemented should they become available and cost effective in the future. I do not think that opportunity should be discounted but neither to I consider that it prevents a safe and effective solution from being applied now.



Further reading 


Contact QLDC

The Council will be deciding whether or not to chlorinate after considering community feedback on the proposed annual plan for 2017-18. Submissions have now closed, but if you would like to contact your representative from the Council you can find their contact details here.

Alternatively if you have any questions we encourage you to contact QLDC directly by calling 03 441 0499 (Queenstown), 03 443 0024 (Wanaka) or emailing us at