Adelaide woman Deborah Pilgrim says the kindness of strangers who helped find her after three days lost in the bush is "overwhelming".

Key points: Deborah Pilgrim went missing on Sunday morning near Sedan

Deborah Pilgrim went missing on Sunday morning near Sedan A local property owner remotely monitoring his security cameras noticed "SOS" written on his driveway

A local property owner remotely monitoring his security cameras noticed "SOS" written on his driveway Police searchers found Ms Pilgrim safe and well about midnight last night

SA Police said Ms Pilgrim, 55, was found safe and well in dense mallee scrub in South Australia's eastern Mount Lofty Ranges about midnight last night.

The Surrey Downs woman had last been seen about 6:00am on Sunday after a party with friends at a campsite on a rural property near the town of Sedan.

Ms Pilgrim was taken to the Angaston Hospital in the Barossa Valley but police said she appeared to be in "good health".

Deborah Pilgrim with her partner, Harry Willcox, after arriving home. ( ABC News: Stacey Lee )

She returned home about 10:20am, driven by her partner, Harry Willcox.

"It's overwhelming, really, the kindness of everybody," Ms Pilgrim said.

Ms Pilgrim said she went for a walk and before she knew it, she was lost.

"I just kept wandering and laid low at night," she said.

"I tried to stay out of the sun and stay alive, I just knew that it was my job to stay alive.

"I thought 'somebody is going to think I've been kidnapped or something' because it's not something I would do."

Police say Sedan property owner Neil Marriott, intermittently monitoring CCTV cameras on his bush block, saw "SOS" had been written on his driveway.

He told police, who began another search and found Ms Pilgrim shortly after on a neighbouring property where she had access to water.

She was about 7 kilometres from where she was reported missing.

Property owner 'feared the worst' for woman

Mr Marriott, of Woodside, told ABC Radio Adelaide the CCTV cameras had only recently been installed by his son after several break-ins.

His son, Phillip Marriott, who runs a security business in Mount Barker, called him on Tuesday afternoon to get him to look again at the live footage from the cameras.

"So I did and there was the SOS written in the ground, which wasn't there the day before," Mr Marriott said.

"So I put two and two together and called police, but by the time they were able to get out there it was dark, so they found the SOS on the ground but then they also found a hoodie jacket which obviously belonged to the lady."

Neil Marriott showing an app on his mobile phone with CCTV of his cottage near Sedan. ( ABC News: Lincoln Rothall )

Mr Marriott learned she had been found through a text message from a police officer based at Swan Reach.

"He just said thanks and she had been found safe and well about 1km from our property," Mr Marriott said.

"I'm so pleased she was able to find water because I feared the worst for her — I really did."

Police search bushland near Sedan on Tuesday. ( ABC News: Brittany Evins )

Thorough search of bush and farm area

The search began on Sunday and involved police on foot, on horses and on motorcycles, along with SES volunteers.

They had planned to return for a fourth day of searching today.

Ms Pilgrim's hoodie jumper as seen on CCTV. ( Supplied: Phillip Marriott )

Murray Mallee local service area Superintendent James Blandford said police were "tickled pink" to discover Ms Pilgrim.

He said she was found outside of the search area.

She found an unoccupied building with water, possibly on Tuesday.

"It's just fantastic that the community responded in such a positive way and was able to use the beauties of technology to help find Deborah and good on her for having the nous for doing the SOS in front of the CCTV camera," he said.

Senior Constable Rebecca Stokes said Ms Pilgrim's good health was "quite remarkable after her ordeal".

"We just want thank that property owner and also SES volunteers and the numerous local property owners," she said.

"Many of them came out and searched their own properties on foot, quadbike and horseback over the last couple of days to help us with this search.

"There has been a massive search of a massive area so really just a great result all around."