A woman missing for three days has been found alive after a landowner checking on security camera footage spotted an SOS message on his dirt driveway.

Deborah Pilgrim, 55, disappeared on Sunday morning in dense bush at Sedan, about 100 kilometres north-east of Adelaide, where she had been camping with friends.

She was found about midnight on Tuesday after nearby property owner Neil Marriott saw that someone had written SOS in the driveway of his bush block.

Mr Marriott, who lives about an hour away in Woodside, told ABC Radio Adelaide he spotted the dirt message on footage from security cameras that had recently been installed on his Sedan property, following several break-ins.

Deborah Pilgrim was found late on Tuesday after leaving an SOS message on a remote driveway. Photo: ABC

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

“I put two and two together and called police, but by the time they were able to get out there it was dark,” he said on Wednesday morning.

“They found the SOS on the ground, but then they also found a hoodie jacket which obviously belonged to the lady.”

Ms Pilgrim was found on a neighbouring property, where she had access to water, police said. She was about 7 kilometres from the campsite where she had last been seen.

She was taken to Angaston Hospital in the Barossa Valley as a precaution but returned to her Surrey Downs home on Wednesday morning.

“I would like to thank everybody who has helped to find Deb,” her partner told waiting media as they arrived.

Home at last. Deborah Pilgrim's emotional thank you to searchers as the Surrey Downs mother reveals how she survived three days lost in scrubland near Sedan. The latest in 7NEWS at 4pm and 6pm. https://t.co/GvVXGUNEga #7NEWS pic.twitter.com/iR7yNgFcSK

— 7NEWS Adelaide (@7NewsAdelaide) October 16, 2019

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

“He just said thanks and she had been found safe and well about a kilometre 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.”

A wide-scale search of the area was raised after Ms Pilgrim went missing, utilising resources including the police helicopter, mounted operations, STAR group, SES volunteers and drones.

The search was set to resume for a fourth day of searching before she was found.

Senior Constable Rebecca Stokes told the ABC that 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.”

-with agencies