What you need to know about our network and how we're working to maintain a safe drinking water supply.
What the Drinking Water Standards say
In order for groundwater to be provided without the need for treatment, three criteria must be met:
- The bore water must not be directly affected by surface or climatic influences (i.e. the water is at least a year old, by which time any pathogens will have died)
- The well head must provide satisfactory protection to prevent contamination of the water supply
- E. coli must be absent in the bore water.
To meet the first criteria, every five years we test the age of the water in a selection of wells and undertake groundwater modelling of our aquifers.
To meet the second criteria, we have an independent expert in well head security regularly assess all well heads, with each well head inspected once every five years.
Our regular testing for bacteria and lack of transgressions provides the evidence to satisfy the third criteria.
This information is provided to the Drinking Water Assessor to demonstrate that our groundwater supply is secure.
About our water infrastructure
The Council has 104 wells with below ground well heads and 36 wells with above ground well heads. There are 53 pump stations that supply water across the network.
A well head is the physical structure at the top of the well that connects to the water supply network.
All new well heads are built above ground to improve the resilience and safety of wells and the security of water supply, and this has been Council’s approach for all new wells drilled since the earthquakes.
The impact of the Havelock North drinking water contamination event
After the earthquakes, the Council was granted provisionally secure status for its water supply. Well head security assessments were done with 20 per cent of the well heads being assessed each year, meaning the entire network was completed over five years.
In May 2017, the Havelock North Drinking Water Inquiry Stage 1 report was released. It identified below ground well heads as a possible source of water contamination. The Council asked its maintenance contractor Citycare to investigate the condition of its below ground well heads.
In August that year an improvement programme began to address the potential pathways for contamination via well heads – sealing cracks, raising air vents etc.
In December 2017 the Stage 2 Havelock North Drinking Water Inquiry report was released. That month the Council’s well head security expert did assessments of 25 well heads. They applied a stricter interpretation of the standards and found that the well heads were no longer regarded as being secure from contamination. Later that month, the Drinking Water Assessor advised Council that the groundwater supply was no longer provisionally secure.
In January, on the advice of staff and the Medical Officer of Health, the Council decided to temporarily chlorinate the water supply for up to 12 months while well head remediation was done.
What the government is doing
The Government is undertaking a nationwide review of Three Waters and considering its response to the recommendations of the Havelock North Drinking Water Inquiry. These include the formation of a single regulatory body and reviewing the Drinking Water Standards. Among the recommendations of the Havelock North Drinking Water Inquiry are:
- The mandatory treatment of drinking water supplies in New Zealand to protect all water supplies from bacterial and protozoal contamination
- Removing the “secure bore water” status from the Drinking Water Standards of New Zealand
- Prohibiting new below ground well heads
- The creation of a single water regulator in New Zealand.
- That the Drinking Water Standards for New Zealand be reviewed.
What we are doing
We are upgrading our well heads so they meet the new, stricter interpretation of the Drinking Water Standards. Once well heads are secure, temporary chlorination can stop at those sites.
We are also looking at whether UV light is an appropriate treatment method at some sites. UV treatment provides protection against contamination but does not have the same effect on taste and smell as chlorination.
Some well heads will be converted to above ground well heads to further improve their security and to make them easier and safer to access for maintenance. There will be some new wells drilled. Other work will be done to provide protection from contamination in line with the stricter interpretation of the standards.
The immediate work we're doing is shown on the map below under Stage 1 works. There is more detail about this work on the well head improvements webpage.
Our work is being planned so that whatever option we do to remediate our well heads or provide an alternative to chlorination, it will meet the best practice for water supply infrastructure.