Auckland's water company says households which are three months or more behind with their bills owe $6 million.
Watercare Services is facing political opposition as it works on a policy allowing it to cut supplies to a trickle for those who can, but refuse, to pay up.
Watercare, owned by the Auckland Council since November last year, has been supplying water to much of the region and billing consumers directly.
It says overdue payments amount to $42 million - and $6 million of that is owed by households more than three months behind.
Watercare says a policy it is working on would see it cooperate with those facing hardship, but keeping the option of restricting supply to those who can pay, but choose not to.
One councillor, Cathy Casey, says this defies previous council directives and on Thursday she will ask the council to ban Watercare from using restrictions.