Napier City Council is asking residents to limit their wastewater, with heavy rain meaning the city's wastewater system is at risk of overflowing into Ahuriri Estuary.
CEO Wayne Jack said they were managing the situation, and just needed residents to give them a hand.
"We're just asking the Napier people to try to help us keep on top of it with the heavy rainfall we've been having.
"We're managing it as best we can, but that's why we're asking people just to give us a bit of a hand during this next period when we've got some heavy rain.
"If people, for instance, just avoid washing clothes tonight through the washing machines, and just, if you're doing a number one just hold whatever is in the toilet for a bit," Jack said.
"Those little things will make a big difference."
In the past, Napier has had problems with wastewater and sewage combining and overflowing into Ahuriri Estuary.
That had not happened today, and the council was hopeful it would be avoided with the public's help. Monitoring systems allowed the council to assess the risk of overflows.
"The problem we have is because of the large amount of inundation that gets into the wastewater network, it's all the stormwater which gets into the wastewater.
"That's what we want to avoid."
He said council had set aside funds in the Long Term Plan to fix the issue.
"We're aware of the issue and that's why council has made the commitment in the Long Term Plan with a significant investment to addressing this.
"These things aren't a quick fix."
In the 24-hour period leading up to NCC's request Napier experienced 51.4mm of rain.
A spokesperson for Hawke's Bay Regional Council, which monitors water pollution in Ahuriri Estuary, said they were aware of the situation.
"We have been in touch and NCC are keeping us informed."
Meanwhile an NZTA spokesperson said they are monitoring State Highway 2 outside the Ravensdown fertiliser works at Awatoto which was flooded since early morning yesterday.
The spokesperson said they are unsure what is causing the flooding but believe it was the fall of heavy rain in a short space of time.
The agency would continue to monitor the situation and will update social media pages and accordingly.
As of last night they were not planning on closing the road.