There appears to have been no health implications following a nitrate contamination in part of Christchurch's water supply.

The bore in Wrights Road in Addington had high nitrate levels in both November last year and February this year.

CDHB medical officer of health Dr Alistair Humphrey says high nitrate levels tend to only affect babies under six months old, if their formula is mixed with the contaminated water for an extended period of time.

"We have checked with the paediatric department and there's been no signs of nitrate poisoning in small babies in Christchurch in the last year or so."

Humphrey said there was low risk of nitrate poisoning.

Council Head of three waters and waste John Mackie said it's one of the few remaining shallow bores in Christchurch, meaning it's more susceptible to nitrate contamination.

He said they'll be working on isolating the bore today and have now changed protocol meaning the DHB will be informed of any other cases of high nitrate levels in the water supply.