Judge Collins said Smart was the architect of the approach that used "scare tactics around the fitness of New Zealand tap water".
Judge Collins imposed fines of $355,000 for Love Springs and $200,000 for Mr Smart.
Commerce Commission head of investigations Ritchie Hutton called the offending "nasty and cynical".
"The Commission obtained an injunction to stop the conduct in April 2010, and we are pleased that the Court has now recognised the seriousness and exploitation of the offending by imposing these penalties," he said.
"This offending caused significant harm to the public, " said Hutton.
"The company targeted vulnerable people in their homes by scaring them with false information about the safety of New Zealand's reticulated water network, and then charging them $1,600 for something that comes out of the tap. Scientific evidence shows that the dire health warnings were completely false."
The commission said that Smart has previously been convicted in Australia for similar offending.