But the matter was not without debate, with six of the 16 councillors - Zulfiqar Butt, Karen Naylor, Brent Barrett, Renee Dingwall, Deputy Mayor Aleisha Rutherford and Lorna Johnson opposing the decision.
Cr Barrett said he doubted the option would be granted resource consent.
"Honestly, in 2021 we are signing off on 50 years of continuous discharge to river? That is nonsense. I don't think we are setting ourselves up for resource consent. We are setting ourselves up for a very expensive and difficult next stage," he said.
"It fails to give certainty of progress over time."
Opposition to the motion raised the ire of Palmerston North Mayor Grant Smith. He had supported the motion, along with councillors Lew Findlay, Billy Meehan, Susan Baty, Rachel Bowen, Vaughan Dennison, Patrick Hancock, Orphee Mickalad, Leonie Hapeta and Bruno Petrenas.
Smith labelled opposition last-minute politicking.
"We've sat in these meetings ... I find it unbelievable it is getting painted that we are not going to get out of the river," he said.
"I'm sorry, it is absolute bullocks.
"This annoys me. We have come on a journey and at the 11th hour we are trying to get political mileage on this?"
The option demanded ongoing efforts to further reduce river discharge over the course of the consent, he said.
"This is absolutely going to get us out of the river. Not in the timeframe that a certain councillor or two wants, but it will get there," he said.
"It needs to be done in a managed way that doesn't absolutely make the city bankrupt and brings all our stakeholders with us. This city is going to do fantastic work in this space and I am really annoyed we have got political at the 11th hour.
"If you can't vote for this, I don't know what you can vote for."
Mayor Smith had said it was important that the council adopt a BPO so it could move the process to the next step.
PNCC had originally aimed to have a BPO locked in by June, so it was behind schedule. It was required to have the resource consent lodged with Horizons by June 2022.
Mayor Smith acknowledged the amount of work that had gone into research and consultation, which showed there was opposition to all options.
The common thread was that wastewater had to be treated to a high level.
A consent condition would see 75 per cent of wastewater discharged to land during low river flows, with a commitment to further reducing discharge to river throughout the course of the consent.
The BPO was one of 11 options put forward by a steering group after lengthy consultation with iwi, farmers, neighbouring communities and ratepayers. It had been working through the process since 2017, starting with 36 different options.
Rangitāne, as mana whenua, had been heavily involved in the consultation process and its opposition to ocean discharge was a key factor in that option being dropped.
A condition of the consent application would be that iwi would continue to be involved throughout the adaptive management strategy.
Other options on the shortlist required as much as 2000 hectares - larger than the area within Palmerston North's boundary - although those options carried a lower level of treatment.
Meanwhile, Warburton said it was about finding a BPO first and then finding ways to fund it, not the other way around.
"The first principle is what is the right answer now, and not just now but in the future, and do that in the most responsible way," he said.
Adaptive management was a sensible way to accommodate naturally occurring changes in technology and improvements in design. Technology could also reduce the quantity of wastewater, he said.
It could be used to irrigate parks and golf courses, with applications for industrial use or for agricultural purposes, and could also be used to regenerate existing wetlands.
Meanwhile, the council had pursued resource consent without pre-emption of the current Three Water reform proposal, which if adopted would see a Government body take control and charge for all water, wastewater and stormwater assets.
