Last year Australians donated over 300,000 tonnes to charity op shops, 60,000 of which ended up in landfill.

This National Op Shop Week charities are urging people to donate only good quality, working items that they would be happy to give to a friend.

We've all scored that elusive op shop bargain at least once and revelled in telling people it was snapped up for a steal at the local op shop.

But for every bargain there are thousands more duds that have to be disposed of, at a cost to the charity.

Anna Presser is the General Manager for Social Enterprise with Anglicare WA, she said the week was a reminder to donate, but also to donate wisely.

"The focus for the week is to encourage good quality donations, over time the quality of donations that the charity receives has reduced, so we want to raise awareness of both donating and the quality of what people donate," she said.

"In 2012 Australians donated over 300,000 tonnes of items to charity op shops, so that equates to 13,200 40foot containers.

"Of that though 126,000 tonnes were used by the community, either given away by charities or sold through the charity op shops, 30,000 tonnes were recycled into wiper rags mainly through disability workshops, 42,000 tonnes of low grade goods were exported to developing countries and 60,000 tonnes were unusable and disposed of in landfill.

"The cost of this is borne by the charity, that's why only good quality items should be donated to charity op shops."

Anna said items that are visibly damaged should not be donated.

"When I'm looking at what to donate I like to think 'would I give that to a friend?'.

"As long as it's not torn, damaged or stained, and you would be happy for someone that you know to wear it or to treasure it, that would be my guideline."

The benefits of op shopping are abundant.

"The donor gets to de-clutter the wardrobe and you get to feel good about giving back to the community, it's also good for the environment as the goods are recycled and not going into landfill.

"You're also helping local charities raise valuable funds to provide services in your local community."