Bore water near Christchurch Men's Prison clear after diesel leak

Corrections says further testing of bore water near Christchurch Men's Prison after a diesel leak has returned clear results.

It comes after about 14,000 litres of diesel leached into the ground at the prison on May 24 after the hatch of a fuel tank was left open, potentially affecting the water supplies of neighbouring properties.

Corrections custodial services commissioner Leigh Marsh said a sample taken from outside the prison on June 6 returned a clear result on Tuesday.

Large diesel spill at Chch prison

A sample taken from 200 metres outside the prison perimeter on May 28 tested positive for dissolved hydrocarbon and Corrections visited 40 properties to determine who was affected.

Eight affected neighbouring properties had been told to stop using water from their private bores for drinking, cooking or feeding stock or animals and use water from other sources until the potential contamination was addressed. It remained safe for showering and washing.

Marsh said that advice from the National Public Health Service regarding water use had not changed.

"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."

Marsh said neighbouring residents would be kept informed of test results and it would ensure that they had the water they needed.

Corrections was now working through an updated testing and monitoring plan, with additional bores being drilled on site, and additional testing sites included in its plan.

Results from these tests would help to determine the next steps as it worked with the National Public Health Service to understand when we can see a safe return to normal.