The true cost of dealing with flooding could run into many millions of pounds, councillors have heard.
Brighton and Hove Council has already spent £400,000 on dealing with flooding after record rainfall this autumn.
But Councillor Theobald, opposition leader, told the policy committee on Wednesday night: "It could cost millions of pounds to put right."
He said major improvements were needed to the drainage system in areas such as Patcham and Bevendean where the problems had been worst.
Coun Theobald said that in spite of everyone's efforts, Patcham was still on a knife's edge after more heavy rain this week. The water table was dangerously high.
Environment director Alan McCarthy said surface water was being pumped away from Patcham but pumping had little effect on ground water levels.
He said the problem was how to get that water away from Patcham and into the main drainage system and added: "It will not be easy to resolve."
Mr McCarthy revealed there had been further mud slides on land at Bevendean this week but fortunately action taken by the authorities had prevented homes from being flooded.
Councillors are approaching the Environment Agency asking for help to be given to the two towns.
Environment cabinet councillor John Ballance said: "The agency does not have a high enough profile in Brighton and Hove."
He added: "We pay £1.5 million a year towards flood defences in Sussex and not a penny comes back here."
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