Sports grounds and some roads were closed yesterday and there was minor flooding around Dunedin city.
Emergency services dealt with several collisions on slippery streets in the city, and a large slip closed Highcliff Rd at the Sandymount Rd intersection on Otago Peninsula about 1.15pm.
Contractors said the slip should be cleared today.
The occupants of one Dunedin house were evacuated and several other properties cleared after sewage backed up.
Dunedin City Council water and waste services manager John Mackie said the occupants of the house were evacuated after sewage contaminated the property.
They were moved to a motel and the council sent contractors to clean up.
Sewage had backed up in parts of Mosgiel and in several parts of Dunedin, including Northeast Valley and South Dunedin, Mr Mackie said.
He had heard of it overflowing at only one property.
Pupils at Northeast Valley Normal School were sent home at 11am and students and staff at the Otago Polytechnic Manaaki Student Centre in Harbour Tce were sent home later in the day after sewage backed up.
The problems were caused by a combination of the high tide at 1.36pm yesterday and the heavy rain, Mr Mackie said.
Another high tide was expected about 1am. Contractors were on standby.
It was unusual for rainfall to continue so intensely for so long, he said.
"My colleagues up north are saying this could be a one-in-100-year storm event.
"We haven't got the final analysis for Dunedin, but it feels like it might be of that order here, too."
Swollen creeks closed rural roads across the wider city, including on the Taieri Plain, near Middlemarch and around the city.
State Highway 1 south of Waikouaiti was closed about 6pm when the Waikouaiti River began to flow over the road. One lane reopened about two hours later.
The Dunedin City Council urged residents on the West Taieri rural water scheme to restrict their water use until further notice after debris blocked the intake of the scheme.
Flagstaff Creek overflowed, closing Three Mill Hill Rd linking Dunedin with Mosgiel for a period in the morning.
The Silver Stream, the main concern on the Taieri, did not reach its spillover level and was dropping by early afternoon.
Otago Regional Council environmental manager Martin King said the Silver Stream, which runs alongside Mosgiel, rose more quickly and to a higher level than anticipated.
Dunedin City Council civil defence and rural fire manager Neil Brown, said civil defence monitored the situation all day, but stopped at 6pm as forecasts for overnight rain where not concerning.
