Napier is being warned against rushing to flushing as one of the heaviest daily rainfalls in the city in recent history threatens to force waste water discharges into the Ahuriri Estuary.
The warning was issued via the Council's facebook page about 10.45am, saying there'd been over 100mm of rain overnight and another 64mm was forecast.
"Our wastewater system has been overloaded by over 24 hours of heavy rain," the post said. "If we all work together to reduce the amount of waste water we're producing, we hope to avoid an emergency discharge into the estuary."
"In order to prevent an emergency discharge from the network into Ahuriri estuary, Napier City Council asks that the community flush toilets only when necessary, and hold off using showers, dishwashers or washing machines if possible.
"If an emergency discharge is carried out, this should prevent wastewater backing up and overflowing into city streets and properties.
"Toilets, showers, dishwashers and washing machines all drain into the city's wastewater network, which is also affected by infiltration of stormwater."
An NCC spokesperson said Hawke's Bay Regional Council has been informed of the situation.
"The region has had on average 100mm of rain overnight, and a further 60mm of rain is expected to fall through to 6pm tonight."
Homeowners are also nervously watching rising water in the Tukituki River in the coastal Hawke's Bay settlement of Haumoana.
A Hawke's Bay Regional Council spokeswoman said Hastings has received approximately 90mm of rain in the past 24 hours.
Hastings District councillor Ann Redstone said on Wednesday morning "houses down at the beginning of Haumoana Rd are under threat" due to the rising Tukituki River mouth.
A Hawke's Bay Regional Council spokeswoman said the river mouth in Haumoana was "not blocked".
"There are big swells running which aren't allowing the river water to get out to sea."
She said said there was surface flooding on lawns around Haumoana Rd, but not a "huge risk" to homes.
There was also surface flooding on orchards around Raupare Stream in the Twyford area.
The stream feeds the Clive River.
She said the engineering staff had been working hard overnight to manage control gates and clean the pump stations.
A spokeswoman said that a bedroom in the house was flooded because of the rain.
"Water was coming in from the roof," she said.
Firefighters also helped homeowners on Kirkwood Rd in Flaxmere with a leaky roof.
Hastings Intermediate School told students they could stay home because of the bad weather.
"As a consequence of major flooding in the school playground and more rain forecast, we recommend where possible that students do not attend school today," a post on Facebook said.
"Students that do attend should wear gumboots! To be clear...the school is open but if alternative arrangements can be made today then that would be wise."
Sustained wet weather across Hawke's Bay on Tuesday caused localised flooding, road closures and minor slips.
NZTA on Tuesday evening asked motorists to avoid travelling on SH2 near Tangoio and SH5 Napier-Taupo Rd if possible due to the number of reported slips.
They said that contractors had confirmed minor slips along SH5 Napier-Taupo Rd, and SH2 near Tangoio but were not significantly impacting the road and to only travel if necessary.
Flooding at Makahu Rd, near Puketitiri, 56km northwest of Napier, resulted in the closure of Makahu Rd ford on Tuesday until further notice.
MetService meteorologist Kyle Lee said on top of periods of heavy rain, thunderstorms were possible for the region.
For a warning criteria to be put into place there needs to be either 120mm of rainfall in a 24-hour period or the rainfall intensity needs to be 10mm in an hour, he said.
Clifford also recommended drivers, including motocyclists and cyclists, keep their lights on while driving during the day, as a safety measure.
"We haven't had any problems yet, but wandering stock can be an issue in these conditions, particularly on our narrow rural roads."
HOW ARE THE VINES?
The belts of heavy rain may not have created any damage to the region's grape vines but they have set the scene for "plenty of work" according to winegrowers.
Mission Estate viticulturist Steve Wheeler said while the two days of rain had created plenty of surface water across nearby paddocks it had created no major issues for the vines.
"But it creates a bit more work for us as the grass and weeds will really grow so there will be lots of mowing."
Hawke's Bay Winegrowers chairman Michael Henley agreed.
"If we get a good patch of warm weather over the next week it's going to take off."
He had not heard of any major serious surface flooding across the region's vineyards at this stage, although with rain continuing to linger it was something of a wait and see situation.
The rain had arrived at a time when many viticulturists would have be considering beginning some irrigation.
"We would have started thinking about that," Wheeler said.
"Good little drink of water," was how Henley put it, adding that on the whole the vines, which were not yet fruiting, were sitting "pretty okay".