"It's time to stop the spinning and get back to delivering core council services for ratepayers," he said. He suspected the polling was being done for "purely political reasons".
A further $212,237 has been spent on around 15,827 panellists that the council use to "have their say on a wide range of council issues, activities and plans".
Brown's own office splashed $162,985 on UMR Research pollsters over two years.
"This was commissioned to assist the mayor to fulfil his role leading the development of plans, policies and budgets," a spokesman said.
Brewer said the $5.1m figure was only the tip of the iceberg.