The regional development minister told the assembly he was fearful of further flooding due to a new weather warning issued by the Met Office, on 2 July 2012.
Danny Kennedy was responding to an urgent oral assembly question tabled by Stewart Dickson of the Alliance Party.
The Fire and Rescue Service dealt with more than 700 flood-related call-outs in greater Belfast following a series of heavy downpours over a two-day period at the end of June.
At the height of the flooding, many roads were impassable and about 1,000 homes were left without power.
Mr Kennedy said he understood the frustration and distress people felt and said there was a need for effective coordination between agencies.
He said he was looking at increased investment for drainage in the worst effected areas.
Mr Dickson said drainage systems needed to be brought "into 21st century".
Sinn Fein's Sean Lynch said processes had failed and Sammy Douglas of the DUP said there was a "need for exceptional action to deal with this".
Ulster Unionist Michael McGimpsey said householders in his constituency of South Belfast were "distressed" at raw sewage flowing through their homes.
SDLP leader Alasdair McDonnell, said what he had witnessed had been "horrific" and commented on a "total failure of agencies to work together".