Update - Friday, 4 July
Please attribute to Leigh Marsh, Commissioner Custodial Services:
On Friday 4 July, the National Public Health Service advised Corrections and users of neighbouring private drinking water bores that they no longer needed to restrict their use.
Groundwater monitoring has continued and after reviewing all data from monitoring bores on prison land and other downgradient sites, as well as a preliminary conceptual model of the diesel spill, National Public Health Service and Environment Canterbury have advised us they believe there is no evidence to suggest potential for groundwater contamination outside the prison property boundary.
I want to thank affected neighbours for their patience while this situation was being resolved.
Update – Wednesday 25 June
Please attribute to Leigh Marsh, Commissioner Custodial Services
On 6 June we visited the approximately 40 neighbouring properties, many of which are vacant or were unoccupied at the time. Initially we made contact with nine properties, eight of which were using a private water source. Subsequently we have made contact with 14 other properties, sharing with them the advice from the National Public Health Service and offering water if needed.
We are continuing to keep all 23 properties updated and there are currently 11 households that have been supplied with approximately 1700 litres of bottled drinking water, as well as one property which has received two 1000-litre containers for livestock. A small amount of the bottled water was initially provided by Corrections from stock we had on-hand, but otherwise this is all being supplied and funded by Downer and has so far cost them approximately $3,000.
When a bore is first drilled, soil samples are taken to test for the presence of diesel. Groundwater samples are then regularly taken from the bore to identify if any hydrocarbons have reached the water table.
A bore was drilled where the diesel spill occurred inside the prison grounds and a soil sample was taken. Unsurprisingly, this returned a positive test for diesel on 12 June. The test revealed that diesel is present 3-6 metres deep at this location. There has been no diesel present in the soil samples taken from the drilling of other bores, which is a positive indication.
Groundwater samples taken from this bore at the spill site have all tested clear for any hydrocarbons. The groundwater sample which tested a weak positive was taken from a bore approximately 300 metres from the spill site, but further samples from this bore and each of the others have all consistently returned clear results.
Update - Thursday 19 June
Please attribute to Leigh Marsh, Commissioner Custodial Services:
Tests across all groundwater bores sampled continue to show clear results.
We have continued expanding the number of sampling bores, with a total now of 11 sampling bores.
Soil testing around one bore has confirmed the presence of diesel to a depth of between 3-6 metres. This is the location where the spill occurred.
The advice from the National Public Health Service remains unchanged regarding water use. We continue to work with them and technical experts towards a return to normal for the small number of affected neighbours reliant on private bore water. Our team is keeping them updated regularly and remains committed to providing water to those who need it.
Update – Friday 13 June:
The below statement can be attributed to Leigh Marsh, Commissioner Custodial Services:
Ongoing groundwater tests from both inside and outside the prison continue to all return clear results.
Currently the advice from the National Public Health Service remains unchanged regarding water use. We continue to work with them and technical experts towards a return to normal for the small number of affected neighbours reliant on private bore water. Our team is keeping them updated regularly and is committed to providing water to those who need it.
We have now expanded the number of sampling bores, adding new data points to support the National Public Health Service’s decision on when normal water use can resume.
The water supplies in Christchurch Men’s Prison (CMP) and Christchurch Women’s Prison (CWP) are interchangeable and we can alternate between them based on operational requirements. We continue to take a cautious approach and currently have CMP operating on CWP’s water supply.
Update – Tuesday 10 June:
The below statement can be attributed to Leigh Marsh, Commissioner Custodial Services:
The sample taken from outside the prison on Friday 6 June returned a clear result today.
The sample taken from the same site on 28 May remains the only positive result from our testing. While this is a good sign, we are still taking a cautious approach and testing will continue.
In the meantime, the small number of impacted neighbours are still advised the National Public Health Service advice regarding water use has not changed at this stage. We will stay in regular contact with them while testing progresses to keep them updated and ensure they have the water they need.
We are now working through an updated testing and monitoring plan, with additional bores being drilled on site, and additional testing sites now included in our plan.
Results from these tests will help indicate the next steps as we work with the National Public Health Service to understand when we can see a safe return to normal.
Friday 6 June:
The below statement can be attributed to Leigh Marsh, Commissioner Custodial Services:
Corrections has advised a small number of neighbouring properties at Christchurch Men’s Prison to temporarily stop using private bore water for drinking and cooking as a precaution after diesel entered the ground at the prison. This does not impact residents in the area on town water supply and it does not impact anyone in the wider Christchurch area.
Approximately 40 properties were identified as potentially being on private bore water and have been visited this afternoon. Not all these properties had residents living there, and some properties are on town supply so are not affected. Bottled water has been provided to those residents who requested it.
We encourage all those who have been contacted by us to follow the advice of the National Public Health Service and Environment Canterbury in relation to the use of water for drinking and cooking. This advice was provided directly to neighbours by Corrections’ staff this evening.
If a property has not been visited by Corrections, or had a letter left in their absence, they are able to continue using their bore water.
On 25 May 2025, a significant amount of diesel exited one of the prison’s fuel tanks, which resulted in diesel entering the ground below one of our buildings. Corrections immediately engaged with technical experts who began testing nearby bores, with all prior results returning negative results.
We also notified key agencies including Environment Canterbury, Taumata Arowai, and Fire & Emergency NZ.
On 6 June 2025, we received a positive result on one of the tests taken from a bore approximately 200 metres outside of the prison perimeter.
As a result, we have visited approximately 40 properties – by door knocking and leaving a letter with further information – and have advised a small number of occupied properties that they should stop using water from their private bores, and use water from other sources. Corrections will be working with these residents directly to provide an alternate source if they do not already have one.
These properties have been identified as their bores are situated downgradient from where the diesel has entered the ground.
If a property has not been visited by Corrections, or had a letter left in their absence, they are able to continue using their bore water. As previously mentioned, this does not impact residents in the area on town water supply and it does not impact anyone in the wider Christchurch area.
While Corrections has received a positive result, we are continuing to undertake further testing and analysis. We will continue to keep impacted residents updated.
Notes:
- The town water supply is not affected.
- All tests to date have returned a negative result, apart from the result we received on 6 June 2025, which confirmed the presence of dissolved hydrocarbons in the bore approximately 200 metres outside of Christchurch Men’s Prison.
- The nearest residential-use bore is approximately 1.4kms from where the diesel entered the ground.
- We are undertaking additional tests to confirm the result, and will keep impact neighbours updated.
- Of those properties that were visited this evening, many were vacant, and the large majority were using the town water supply, not bore water.