Multimillion-pound flood protection schemes on Teesside were "overwhelmed" during torrential rain on Friday, Northumbrian Water said.
Homeowners in Redcar criticised a water storage system, completed last year, after 60 homes were flooded.
Alistair Baker from Northumbrian Water said the "ferocity" of some storms was "well in excess of the design capabilities" of defence schemes.
Cleveland Fire Brigade received 240 calls for help during the downpours.
Families living at St Joseph's Court in Redcar were among those worse affected.
'Not complacent'
Simon Welch, whose home was flooded, said a storage tank was supposed to relieve the main sewer.
Mr Baker said: "I can say that in that area had it not been for work that was completed, even more homes would have been flooded.
"We are not complacent, we are doing all we can but there is only so much you can do and that work has to be prioritised so that money is spent appropriately and invested in the best way to benefit the most people in as many areas as possible."
Saltburn, Skelton and Skinningrove were also badly hit during Friday's flooding.
