Donate only what you would give to a friend

A dead shark, used dentures and a prosthetic limb are just a sample of the odd items dropped at charity doorsteps across Australia, prompting National Op Shop Week founder Jon Dee to urge good Samaritans to donate correctly.

"The majority of donations are fantastic and help to fund vital community services," he said.

"But if you give them something that's unsellable, then the charity op shop has to pay to dispose of that item."

Mr Dee said charities, including the Australian Red Cross, Vinnies and Salvos stores, were spending millions of dollars each year to dispose of dirty nappies and stained sheets.

The Salvation Army spends $6 million each year on disposal fees, money WA regional manager Sean Burgess said could be better spent providing meals and supporting people affected by domestic and family violence, alcohol, drugs and gambling.

"We often have items which are completely unsaleable left at our stores after hours, the biggest issues being e-waste and mattresses," he said.

"We are required to pay to dispose of these goods and it diverts considerable funding from the community programs of which we assist."

With spring on the horizon, Mr Dee called on people to "op till you drop" during National Op Shop Week from August 23 to 30.

"We need people to donate good quality clothing and other goods to their local charity op shops and we need people to purchase them so that money can be raised to fund vital services," he said.

The rule of thumb is to donate only things you would be happy to give to a friend.

"Call ahead if you are unsure," he said.