Earthquakes could have contributed to the contamination of Havelock North's water.
The governments inquiry panel has heard today that the e-coli contamination, which struck down nearly six thousand people with campylobacter, has come from the Mangateretere Pond.
Water resource scientist, Brydon Hughes says something has changed in the aquifer system which has led to a contamination event of this size, which has never occurred before.
He says recent earthquakes may have changed the pathways in the aquifer.