Under the campaign, surveillance cameras have been installed at local op shops and messaging about donating responsibly has been included on signs, posters and bags.

The charities are facing illegal dumping on a daily basis with items left either outside premises or beside charities.

Cessnock City mayor Bob Pynsent said he hopes the campaign will encourage people to think more carefully before donating.

"If you are unsure about whether your donations are of saleable quality, please go into the op shops and ask if the item is wanted," Cr Pynsent said.

"A bit of extra care and effort from everyone in the community can make this issue a thing of the past."

The campaign is aiming to reduce the number of unusable donations, which are impacting volunteers time and resources.

To find out more about the impacts of illegal dumping and what you can do about it visit www.cessnock.nsw.gov.au/environment/illegaldumping.