Up to 30,000 households could be hit with an excess water charge in Christchurch.
The city has the highest water use of all New Zealand's major centres, and the city council's infrastructure is not keeping up.
Council head of Three Waters, Helen Beaumont, said it's being proposed that households get charged when they use more than 700 litres of water a day.
She said there would be a fixed rate of $1.35 for every 1000 litres over the limit.
"What we want to do is manage the demand for water, particularly on hot, sunny days," she told 1 NEWS.
"Introducing a charge like this will reduce demand and change behaviour. We've budgeted for about a 30 per cent reduction in that peak demand."
An average household in Christchurch uses around 540 litres a day.
One in five are expected to be stung with a bill and the council could net $2 million.
City councillor James Gough said that, while he supports water conservation, the approach is wrong.
"Everyone has got the same allocation whether it's a 50-square-metre apartment or a 2000-square-metre section. I don't think that is fair and reasonable."
Water New Zealand chief executive Gillian Blythe said the proposed law would make people think twice about how much water they use.
"I think the same thing with your electricity bill or your bank account, if you've got information you can think about what you're doing," she said.
Ron Andrew is an avid gardener and the president of the Canterbury Beautifying Association.
He doesn't know how much water he uses every day but refuses to let his garden go without water.
Andrew said billions of litres of water is lost from the city's broken pipes and the council should focus on fixing it.
"Their objective is to take pressure off their equipment and I don't think that will happen," he said.
The Christchurch City Council is now seeking public submissions.