With the system still vulnerable, and similar rainfall event likely before the programme finished some councillors urged for more to be done to "light a fire under their asses", or encourage action from the city council.
Mr Palmer said the city council were moving as fast as possible with their available resources, however "its still going to take some years".
"We still live in risk period where their assets may not perform as expected, and they may need to discharge sewage either into the streets of Taradale or into the Ahuriri estuary."
Hastings Councillor Rick Barker said this was a problem which predated some of the city council's recent projects.
"We've had all these huge capital investments considered which are salutes to the greatness of the current officer holders but do nothing for the treatment of sewage, or the discharge of raw sewage into the estuary when there is a moderate amount of rain.
"Something needs to change here."
On whether council had any interim solutions, yesterday NCC director infrastructure Jon Kingsford said in the event of a prolonged major weather event like April's, "mitigating risks to human health will always take priority over the condition of the estuary environment".
However a discharge would only ever happen again as a very last resort, he said.
"At the present time, our water specialists are prioritising urgent upgrades to our drinking water network. Wastewater is on the radar, of course, and we will continue to work towards coming up with a successful long-term solution for our network."
Napier is not the only Hawke's Bay council to have discharged wastewater into waterways.
During his opening speech to council, chair Rex Graham remarked it was "simply not acceptable to discharge raw sewage into any of our streams, rivers or estuaries".
"This practice is due to poor prioritising of capital, under-engineering, neglect and incompetence and all this must stop."
In a separate item yesterday, regional councillors gave permission for a water management internal audit to begin.
Councillors also agreed to amend the audit's scope, narrowing it to focus on local authorities who hold consents monitored by the regional council - being Hawke's Bay's four other councils.
An emphasis had also been placed on water bodies which supplied drinking water to the public, specifically with regard to ensuring the health and safety of the community.
