The National Party is promising the freshwater standards coming into force next week will be "gone by lunchtime" if elected.
The legislation passed this month puts controls on farming practices such as winter crop grazing and feedlots and sets stricter limits on nitrogen pollution.
The regulations were described by lobby group Federated Farmers as "unworkable".
Federated Farmers water spokesperson Chris Allen said: "As drafted many farmers will end up being unable to comply, an outcome we are sure is not the government's intent".
He said the changes were a positive step.
"There's a couple of very minor changes there, there are a whole lot of other changes that will be required, to allow the document to make sense, for farmers to be able to implement it efficiently, but we are open to a discussion with the minister."
Today, minister for agriculture Damien O'Connor announced changes to the winter grazing regulations to make them more practical.
"It became apparent that some of the regulations within the freshwater standards - including ones around winter grazing - need to be adjusted, so we've done that.
"The regulations on pugging depths around fixed water troughs and gateways weren't practical so we have made some adjustments to make them more realistic."
Discrete areas around fixed water troughs and gateways had been exempted.
"We've also amended the definition for pugging to provide more clarity," he said.
O'Connor said there were still some challenges ahead, but he was confident they would get it right.
"Where the regulations are impractical or unclear we will continue to make adjustments."
'Gone by lunchtime'
In a Facebook Live video last night, National leader Judith Collins and agriculture spokesperson David Bennett said their party would do away with the regulations, accusing the government of not liking farmers.
"So, David, can we tonight promise, because this makes me very angry that these people would do this, that we'll get rid of them," Collins said.
"They are gone by lunchtime," Bennett replied.
O'Connor said the comment by Bennett was "stupid".
"It flies in the face of what most farmers and most New Zealanders want."
Labour's David Parker said the comment "gone by lunch" didn't work for Don Brash and would not work now.
"They're trying to shore up their base and instead they're evaporating it," he said.
Greens co-leader James Shaw said if anything, the regulations didn't go far enough.
He said the better part of three years was spent going through the contentious issue because National had failed to address freshwater issues adequately.
"National lost the last election in part because they had failed so dramatically on freshwater, if they want to turn back the clock and go back to the old dirty polluting ways of the past that is up to them, but they lost on that basis," he said.
The comments were being described as reckless and dangerous by the Green Party's environment spokesperson Eugenie Sage.
"The new leadership of the opposition is trying to take their party back decades by saying rules to look after the health of rivers 'would be gone by lunchtime' if they were in power," she said.
Sage said the Greens were committed to strengthening the standards to make sure nitrogen limits are based on the best science and that regional councils have enough resources to ensure healthy rivers.
"New Zealand's valuable food and fibre exports rely on our clean green reputation internationally, it's important that environmental safeguards are upheld to help maintain that.
"The opposition wants to throw out these safeguards, yet have no plan to clean up waterways and stop pollution in urban or rural streams and rivers," she said.
Later today National seemed to back-pedal on the comments.
When asked for clarification on David Bennett's 'gone by lunchtime' comment National's environment spokesperson Scott Simpson said it was a "colloquial way of putting it."
"Essentially, there were nine issues that were passed by regulation and those issues we think need review and in some cases repeal," he said.
Simpson was pleased changes to the regulations had been made today.
"For there to be literally a further watering down of the water reforms, I think goes to show how out of touch the current government is with farmers in the paddock," he said.
He said if National gets elected it would be listening to the farming community, because the current government had stopped engaging with farmers at a practical level.