Jeremy Corbyn visited Rhydyfelin in Pontypridd this afternoon to meet residents affected by the flooding caused by Storm Dennis.
The Labour leader spoke with one woman on her doorstep who described hearing a loud bang "like an explosion" during the early hours of Sunday morning, before the floodwaters hit her home.
"It was awful", she told him.
He met another who told him the water "went from the bottom of my boots to my waist in about 30 seconds."
Hundreds of homes in south Wales were left underwater after Storm Dennis battered the country over the weekend, prompting South Wales Police to declare a "major incident".
Mr Corbyn told reporters after his visit: "I've met a lot of residents and heard a great deal from them about the severity of the flood and the damage to their homes."
He added: "What's been great is the way the community's come together and supported each other, that's fantastic, but the issue is how do we prevent people's homes being flooded in the future and build better flood defences?
"The Welsh Government has invested a lot in flood defences, well done them, but there are big issues facing the whole country of climate change which does mean that these horrific weather events are likely to become more frequent."
Ahead of his visit to south Wales, Mr Corbyn described the UK Government's response to the recent flooding "wholly inadequate" and criticised Boris Johnson's decision not to visit any of the areas affected.
In response, the UK Government accused Mr Corbyn of trying to "politicise" the floods.
Environment Secretary George Eustice said: "Jeremy Corbyn shouldn't be trying to politicise the floods, he should be backing the Government's move to support and work with emergency personnel who are working tirelessly to help everyone affected.
"We are investing £2.6 billion in flood defences, which have already protected 200,000 properties that would otherwise have been caught out by flooding."