The government’s inquiry into the contamination of Havelock North’s water now knows what caused it, but not exactly how it got there.

The hearing is determining how nearly 6000 people got struck down with campylobacter from the township’s drinking water last August.

Scientists have today revealed that the e-coli came from sheep faeces on paddocks surrounding the Mangateretere Pond, just 90 metres upstream from the bores, which then flowed through the aquifer.

Tony Cussins from Tonkin and Taylor said they’re unsure if the e-coli got in through a hole in the bore, or through the bore’s screen.

Stephen Swabey from the Hawke’s Bay Regional Council said dye testing shows the transfer from pond to bore wouldn't have taken long.

He said it only took 26 hours for the dye to travel through the aquifer.

Water resource scientist, Brydon Hughes said something has changed in the aquifer system which has led to a contamination event of this size, which has never occurred before.

He said recent earthquakes may have changed the pathways in the aquifer.