Have you found dissolved lead in the drinking water?
Out of almost 200 water samples taken in September and October 2019, only three samples exceeded the Ministry of Health's maximum acceptable value (MAV) for dissolved lead. The MAV is a health limit based on the maximum amount of dissolved lead considered safe for a bottle-fed baby to consume each day. It is based on babies' consumption because they are considered to be the most sensitive population group.
What is the public health assessment of dissolved lead in the drinking water?
We notified the Canterbury Medical Officer of Health, Dr Alistair Humphrey, about the results of our lead-sampling programme carried out in September and October 2019. He advised that the public health risk was extremely low and close to nil.
If you are concerned, you can contact your GP for professional medical advice.
When was it discovered that dissolved lead had exceeded the health limit?
The risk of dissolved lead in the water from lead-jointed pipes was identified as part of our revised Water Safety Plan, which was completed in September 2019 under the Ministry of Health's new framework for assessing risks to drinking water.
Sampling of water back in 1996/97 as part of a routine assessment of water quality did not detect any lead levels above the maximum acceptable value, or even half of that value. Because of this, dissolved lead was not identified as a risk in the previous Water Safety Plan and we were not required to test for it as part of our routine monitoring.
Is it still safe to drink water from the tap if it's supplied through lead-jointed pipes?
Yes, the water is still safe for everyone to drink, including babies, children and pets. You don't need to change anything about the way you use or consume your tap water.
Traces of copper and lead can accumulate in drinking water that has been sitting for a long period in contact with metal plumbing fittings. Although the health risk is small, the Ministry of Health recommends you run your tap for a few seconds each morning, or after a long absence from your property, before drinking or washing dishes. This is to remove any metals that may have dissolved from your private plumbing fittings. For the purpose of water conservation, it's suggested you use this water for watering plants.
This simple precaution is recommended for all households in New Zealand, including those on public and private water supplies in the Christchurch and Banks Peninsula area.
What is the Council doing right now about its lead-jointed pipes?
We are reducing the use of lead-jointed pipes in the network, including taking some out of service and temporarily re-routing water through lead-free pipes. We are also continuing to take water samples so we can understand the extent of the issue and whether there are any changes over time. In the medium term, we will also speed up the replacement of lead-jointed pipes through our pipe renewals programme.
Is chlorine treatment of the water causing the lead joints to dissolve?
We can't say for certain whether chlorine treatment is a contributing factor to dissolved lead in the water.
Why do we still have old and damaged pipes supplying drinking water in Christchurch?
The Canterbury earthquakes caused significant and widespread damage to our drinking water supply network. We are working hard to prioritise and catch up on repairs and renewals for our underground pipes and other water supply infrastructure. The task is massive and complex, requiring significant time and investment. As we work, we are also bringing the network up to new, best-practice standards to make sure it is resilient and ready for the future.