Workers have to pick-out an estimated 400,000 dirty nappies wrongly put into recycling bins each year in Norfolk.
The Norfolk Waste Partnership (NWP) has revealed the figure as part of its campaign to stop people from disposing of them incorrectly.
It said used nappies were contaminating otherwise clean recycling, making it unusable, while also posing a health hazard to those tasked with picking them out by hand.
The partnership is asking people to dispose of used nappies in the normal rubbish bin.
Paula Boyce, from the NWP, said: 'We do understand there will be many genuine reasons why people put nappies incorrectly in their recycling bin. People don't realise the problems nappies cause.
'Many people mistakenly think nappies, used or unused, can be recycled because they are made from paper pulp, but they can't.'
The partnership said an estimated 400,000 used and dirty disposable nappies end up at the Materials Recovery Facility in Costessey each year.
Used nappies have to be identified and sorted out by teams of workers at the facility prior to all recyclable items being separated into raw material.
Vice chair of the NWP, councillor Andy Grant, said: 'It takes just one nappy to contaminate recycling. We want to make sure people understand why putting nappies into their recycling bin is wrong.
'Nappies badly contaminate everything else in there and lower the quality of our recyclable material. No one wants to see a bale of paper with a dirty nappy in it.'
'Having to remove dirty nappies from the recycling is also extremely unpleasant and unhygienic for our workers.'
Recycle for Norfolk is working with many of the county's ante and post-natal organisations, health and family support agencies, as well as local councils, community groups and waste collection crews to reinforce the need to keep nappies out of recycling.
The NWP will be spreading the campaign message that nappies need to be put in the rubbish bin where they will be properly disposed of.
The Norfolk Waste Partnership (NWP) is made-up of Norfolk's county, district, borough and city councils, as well as Norse Environmental Waste Services (NEWS)
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