The break on December 30 was probably caused by the Bridge Hill water main being hit by a large tree, blown over in high winds, Central Otago District Council water services manager Russell Bond said.
Four homes were affected by flooding with varying amounts of damage.
The broken section of pipe had since been repaired.
A kilometre-long section of the water main, from the pump house near the Alexandra bridge to Kamaka Cres had already been earmarked for replacement before the rupture, he said.
The main was installed in the 1930s and some piping had been laid above ground ''because it was easier than going through rock''.
The council had estimated $400,000 would be needed for the project and that figure had been set aside in the council's long-term plan.
Engineers were being consulted on replacement options.
''The existing pipe goes through some back yards so, of course, we'll be looking at a possible new pathway for the pipe, a new route, possibly putting it into road reserve, and undergrounding the pipes,'' Mr Bond said.
The main dated back to when Aronui Dam was used as the town water supply.
