Rejected household rubbish put out for recycling in the UK has increased by 84% over the past four years, government figures show.
According to a BBC Freedom of Information request, councils were unable to recycle 338,000 tons of waste in 2014-15 - up from about 184,000 tons in 2011-12.
But Department for Environment data shows total recycled waste rose from 10.7m to 11m tonnes a year in the period.
Councils say they are working to stop people putting the wrong items in bins.
The Freedom of Information Request by BBC Breakfast found 97% of the rejected rubbish was incinerated or sent to landfill in 2013-14 - the most recent year for which such figures were available.
Just over 173,000 tons of rejected waste was incinerated or sent to landfill in 2011-12, with the figure rising to 270,000 tons two years later.
In response, The Environmental Services Association's head of regulation, Sam Corp, said: “Contamination of recyclates costs local authorities, and therefore the taxpayer, money and wastes valuable resources that could be recycled. Local authorities and waste companies are working with householders to address this issue, but it is important to keep in context that 338,000 tonnes represents less than 3.5% of the amount of household waste collected for recycling.
“Whilst efforts should and will continue to be made to reduce contamination, we should not forget the progress that has been made to increase recycling in the UK - from near zero in the early 1990s to almost 45% today. Overall, the amount of household waste recycled rose from 9.1 million tonnes in 2010 to 10.0 million tonnes in 2014, while over the same period the amount landfilled or incinerated fell from 13.0 million tonnes to 12.3 million tonnes. The reports in the national press are about the much smaller quantities of material which, although collected for recycling, cannot in practice be recycled because it is contaminated.
“However, this increase in contamination does still highlight the need for a long-term framework from the government to help drive recycling and reuse, and reduce the levels of contamination that have been shown in these figures.”