A group of quick-thinking Dunedin students saved their flat from being inundated with water by putting together a makeshift water course to redirect a torrent about to enter their back door.

Flat member Jack Cranston said when they got home to their Park St house about 2pm today from a trip into town water was rushing into the back of their section from a neighbouring tennis court.

"It was just pouring down into our backyard.

"It was over ankle deep, it was ridiculous," Cranston said.

The six flat members quickly worked out a way to stop it from rushing in through the flat's back door, getting bricks and tiles out of the shed to create a makeshift water course which redirected the water around the house down a bank and on to a road.

 It only took them about 30 minutes to build the water course. The water would have definitely flowed into the house if they had not come up with the plan and executed it as quickly as they did.

"It would have been pretty tragic if we didn't do that."The six flat members are all University of Otago students, aged 20 and 21, and from across New Zealand.