HOME extensions and paving front lawns for car parking added to this week's flooding, Dublin City Council claimed.
Officials have tried to blame homeowners for increasing the risk of flood damage.
The council defended its response to the heavy rains earlier this week, saying it took all measures within its power to protect the city and had reacted promptly to the crisis by implementing its emergency response plan.
The city's drainage system was not designed to cope with the increasing urbanisation of Dublin, particularly the laying of concrete and tarmac over green spaces, executive manager Tom Leahy said.
"The biggest problems are not with the new developments, but with older housing estates built in the 1940s and 1950s," Mr Leahy said.
"When they were built they had a nice green environment, with front and back gardens.
"It was never envisaged that people would concrete over their front gardens for cars or build extensions covering their back gardens. The drainage system was never designed for that."
Front and back lawns provided natural drainage, but the water now had nowhere to go, he added.
Labour TD Aodhan O Riordain said he had some sympathy, but added: "Blaming extensions and driveways, when many flood alleviation schemes are incomplete and people can't get insurance on their homes, is very simplistic."