About 25,000 properties in Grangemouth, Falkirk and the Lower Braes will join the scheme, which the council started implementing last year.
Falkirk Council was the first in the UK to cut general household waste collections to once every three weeks.
Under the new system, the amount of waste discarded by households has reduced on average by 2kg per week.
Council bosses said the service has led to a reduction of about 400 tonnes of material sent to landfill per month, representing a significant saving in landfill tax.
It is estimated that once the whole Falkirk Council area is participating, 9,000 tonnes of landfill material will be diverted to recycling per year, saving £385,000.
Letters to residents will be issued from this week to the third phase areas explaining the changes, followed by a detailed information pack.
Council environment spokesman Craig Martin said: "The new service has been a success thanks to the support of residents who have made the effort to recycle more every week, particularly food waste.
"The increase in recycling means a reduction in the amount we pay in landfill charges and this is a saving we can use elsewhere. Last year we spent £2.5m sending material to landfill, much of which could have been recycled.
"We're confident that this final round of changes will be as successful as the first two and look forward to the support shown by our communities."
The final phase of a project to cut bin collections to once every three weeks is to be rolled out in Falkirk.