Lichfield District Council and Tamworth Borough Council have told residents to stop putting food waste in brown bins for garden waste.
The Lichfield & Tamworth Joint Waste Service used to send food and garden waste to an indoor composting facility, but that process will now move to a cheaper, outdoor composting facility that will treat only garden waste.
Residents have been told to put food waste into their residual waste bins, which are sent to an energy-from-waste facility, or to dispose of it through home composting.
This “one simple change” is expected to save the partnership around £400,000 each year.
Food totalled just 5% of brown bin content and only some 20% of residents used to separate it, according to the partnership.
The councils have put stickers on bins to remind residents about the change and have now put adverts on the side of bin lorries to spread the message.
Cllr Iain Eadie, Lichfield’s cabinet minister for IT and waste management, said: “We hope plenty of people will see the travelling advertisements and other promotional material we’ve created. Because food waste could now contaminate the garden waste we compost, it’s really important that everyone remembers to add it to their black bins from now on.”