The majority of households and businesses are putting their waste into the wrong bin, according to the Environmental Protection Agency.
It has called on local authorities to enforce the roll-out of the three-bin system - compost, recycling, general waste - and educate people on the importance of segregating waste.
Speaking on RTÉ's Morning Ireland, Programme Manager of the EPA's Office of Environmental Enforcement David Pollard said two thirds of the waste that goes into the general waste bin should not go into it, but should be put into the recycling or organic bins.
He said around two million tonnes of municipal waste is produced every year and two thirds of that "doesn't need to be there".
"The critical issue with waste is the segregation of our waste because if we don't segregate our waste, we fail to recycle. If we don't recycle, more of our waste goes into landfill and incinerators. So it's absolutely critical that people segregate their waste," he said.
Mr Pollard said the role of local authorities in protecting the environment is "absolutely crucial".
These are the people on the ground, who are closest to what is actually happening, he said.
The EPA said four local authorities failed to achieve the required standard in at least seven out of every ten environmental enforcement priorities they were assessed on last year.
Local authorities carried out over 197,000 environmental inspections last year.
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In its annual assessment of how well those inspections and enforcements were carried out, the EPA said Waterford, Offaly, Kilkenny, and Wexford county councils were the worst performers in how inspections and enforcements are carried out.
It said these four local authorities have been doing a poor job most of the time, achieving the required standards of environmental inspection "in only 30% or less" of the 20 national enforcement priorities they are in charge of.
These cover waste, water, air and noise pollution, and governance processes.
The EPA said that while combatting illegal waste activities was carried out well by local authorities, household and commercial waste management was the poorest performing area overall.
Only one local authority, Kildare County Council, achieved the required standard in all cases.
The EPA wants a greater focus from local authorities on the roll-out of brown bins for organic waste, farm inspections to protect water quality, and a greater clampdown on the sale of smoky fuels.
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