A national body trying to determine the extent of damage to quake-stricken farms in the Canterbury region says the majority of irrigation systems appear to have come through the event unscathed.
Earlier reports suggested that one hundred and fifty farms were seriously affected by the Canterbury quake and there were
fears that much of the damage was lurking underground.
However Irrigation New Zealand says most farmers spoken to appear to have avoided major damage to their bores and pumping systems, although water quality remained a concern.
"We know there are some seriously damaged ones, but in terms of numbers it appears the percentage is relatively small and localised compared to the total number of wells," Irrigation New Zealand board member and Aqualinc principal engineer Ian McIndoe said.
Farms with shallow bores of less than 50 metres were most at risk of having wells with contaminated water, he said.
"We are warning people there could be some movement around the well casing that allows contaminants to flow down into the side of the casing and into the screen."
"We don't think it's a big problem, but to get your well tested, just in case," he said.
Irrigation New Zealand spokesperson Chris Coughlan said farmers should delay starting pumps for a week if they could.
"One of the blessings is that we have had such a wet winter that there is quite a bit of soil moisture so a number of them (farmers) feel they have a bit of time on their side to not be under pressure to fire up their systems immediately. We are quite lucky in that regard," she said.
Also, well water levels have risen in most areas, some to several metres and there were new artesian flows in places, although it is unclear whether those changes would be permanent, Irrigation NZ said.
BNZ head of agribusiness Tony Arthur said last week it wouldn't be until systems were pressurised that issues below the ground could be understood.
Damage to bores and pumping systems is not covered by the Earthquake Commission.
Cover from the EQC is limited to up to $100,000 for damage to residential property and up to $20,000 for contents, after which private insurance kicks in.
