Up to 150,000 people were out on streets up and down the country in protest against water charges.
The organisers of more than 100 protests expressed delight at the massive turnout, claiming that well over 150,000 people attended, despite torrential rain.
The Right2Water campaign said: "Despite torrential rain, our expectations have been massively exceeded, with well over 150,000 people coming out in every neighbourhood, town and village to send a clear message to the Government: water is a human right, and we demand the abolition of domestic water charges.
"Today showed the strength of public opposition to water charges in communities up and down the country. The time has come for the Government to accept the will of the people, abolish domestic water charges and return to the drawing board. Until they do, the Right2Water campaign will keep up the pressure."
The group said details of a major rally outside the Dáil on December 10 - International Human Rights Day - will be announced in the coming days.
Protestors in Cork today. Pic: Imgur.
Irish Water has faced strong resistance from the public since its inception, and now the level of public anger is becoming visual.
Thousands braved incessant rain in Cork city.
The march took almost an hour and a half to make its way through Cork city centre.
Amongst the politicians protesting was Sinn Fein's Jonathan O'Brien, who said: "The Government needs to recognise the numbers on the streets.
"People are not going to pay, it is a tax too far."
Heavy rain may have affected turnout, but it is estimated that well over 10,000 marched. making it one of the biggest protests in the city in recent years.
Sinn Féin President Gerry Adams was at the rally in Dundalk today, and he said: "Today's Right2Water day of action was a huge success, with positive, family-friendly demonstrations right across the state.
"It is clear that the Fine Gael/Labour Government has totally underestimated the level of public anger at the imposition of domestic water charges and the determination that now exists to defeat them.
"The establishment of Irish Water and the imposition of domestic water charges has been a fiasco from the start.
"Citizens have had enough of relentless austerity, new taxes and charges.They have said loudly and clearly that they will not accept the Water Tax.
"This Government must listen to the people and end its imposition of water charges."
In the West, unofficial figures suggest just under 3,000 marched in Galway, 4,000 in Sligo, while further north it is believed around 10,000 people took part across Donegal.
Elsewhere, Up to 2,500 people came out to protest in Longford town this afternoon.
More than 1,500 people have also marched in Athlone, and another 600 in Boyle in Co Roscommon.
Meanwhile, Sinn Féin senator David Cullinane spoke at the Waterford protest.
He said: "I think there is a general anger at the whole political system, and I understand that because people are frustrated after being lied to by all of the parties who have been in power.
"I am here with Independent TD John Halligan and we work together on these important issues, we can put aside our political differences."
Approximately 5,000 at the Right2Water protest in Letterkenny today. Pic: North West Newspix
In Limerick, around 4,000 people have turned out for the protests.
Participants travelled from across the mid-west to converge on the Treaty City to voice their opposition to the utility tax.
Up to 2,500 people turned out in Roscommon town, while around 1,200 people marched in Shannon and Ennis, with a further 50 in Westbury on the border with Limerick.