Flooding is threatening Leeston homes, has closed schools and residents are being asked to reduce water usage and toilet flushing.
Heavy rain overnight burst the local creek bed, flooding about eight homes and sending volunteer firefighters to their aid with sand bags.
Leeston Volunteer Fire Brigade chief Noel Thian said the local town creek had overflowed ''and of course it's just going into houses''.
Crews were busy sandbagging around eight houses and lifting appliances off garage floors, he said.
''We're handling it pretty well, put it that way.''
Streets around the town were also flooded, forcing Leeston School and Ellesmere College to close for the day.
Leeston principal Lynda Taylor said the surrounding streets were ''swamped'' and when she was called early this morning by the fire brigade the board made the decision to close the school.
While the water had not flooded any of the buildings, the overloaded sewerage systems were the main concern for the 315-pupil school.
They would be assessing the flooding and sewerage situation tomorrow, before deciding when to reopen the school.
Ellesmere College acting principal Robyn Thompson said she was woken at 5.30am by a call from the local fire brigade to say toilets could not be used and the 490-pupil school would have to close.
A Selwyn District Council spokeswoman said residents living in Leeston and Doyleston were asked to minimise toilet flushing and water usage after heavy rain overnight affected the towns' sewerage systems.
''A number of roads in Selwyn District have been affected by snow in the west of the district and flooding in some areas of the east of the district. Motorists should be very cautious when driving.''
- The Press