A 15,000-signature petition calling for a moratorium on bottled water exports was delivered to Parliament this afternoon, and protests were held outside 21 council offices around the country.
The proposal was supported by Labour, Greens, New Zealand First and the Maori Party.
Labour and Greens want a price on freshwater which is extracted for commercial purposes.
Smith said this raised problems about fairness and cost. A total ban would mean some freshwater users were cut off while others were not, and a price on water would add large costs to extensive water users such as horticulture or dairying.
Earlier today, protesters gathered outside Parliament to present the petition to MPs.
Jen Branje, the founder of protest group Bung the Bore, said communities such as Havelock North were struggling to get access to clean, safe water.
"Yet bottling plants come here and take our pure, deep groundwater for free. And while they're taking it, we get nothing."
"We ask why we're forced to drink chlorinated and fluoridated water from our taps while our pure water is shipped off to other countries."
Parker said claims by Environment Minister Nick Smith that trillions of litres of water was produced in New Zealand each year was false.
"He counts the water coming out of national parks, the water in those floods in Auckland that we just saw in the weekend.
"In truth, our very clean water that is clean enough to bottle or drink without treatment is a precious and scarce resource."
He said it was unfair that a public resource could be used for private profit without consultation and without any benefits to the local community.
Green MP Catherine Delahunty called for greater protections for aquifers, and said there should be a price on commercial use of water.
"You want to make a profit out of it, you can pay for it," she told a crowd outside Parliament.
Bung the Bore was formed in Ashburton, where it successfully challenged a plan by the district council to sell the right to extract around 40 billion litres of water.
It said 74 bottling plants in New Zealand had permits to take freshwater for export, and some paid as little as $500 to local councils to get access to the water.