She asked whether, given the "huge" amount of work there will be around the country, if the council would have made a saving having started earlier, compared to if it had begun the upgrades now.
Chief executive Nigel Bickle said as the council is a "long way" into the upgrade programme he is "quite grateful that we are not at the front end of starting a larger infrastructure programme", given the current market challenges and supply chain issues which have bumped up the cost.
Councillor Wendy Schollum said while she was "quite horrified" when she saw the increase in costs, she too was grateful that the council started upgrades when it did.
"I am incredibly grateful that we are not sitting along dozens of other councils around New Zealand who are going to be vying for the same water expertise in and in a market that is red hot and not looking to cool down."
She said while there is "no way" she would support the level of extra spending under normal circumstances, she found in this case it was a "prudent" spend of ratepayers' money.