The Metropolitan Fire Service (MFS) in Adelaide says it is worrying that two girls lost in a stormwater drain raised the alert on a social networking site rather than ringing triple-0.

The 10- and 12-year-old girls updated a Facebook status to say they were lost in a drain on Honeypot Road at Hackham in Adelaide's southern suburbs on Sunday night.

Glenn Benham from the MFS says it was fortunate a young friend was online at the time and was able to call for help for them.

"It is a worry for us because it causes a delay on us being able to rescue the girls," he said.

"If they were able to access Facebook from their mobile phones, they could have called triple-0, so the point being they could have called us directly and we could have got there quicker than relying on someone being online and replying to them and eventually having to call us via triple-0 anyway."

Professor of Media and Communications at the Queensland University of Technology, Terry Flew, says public education campaigns are facing an ongoing struggle to compete with social media.

"I'm sure they [the girls] would have had information provided to them in their schools about who to contact in an emergency, but as we know many things that are learnt in school can go in one ear and out the other," he said.

"For these kids, by the sounds of it, being on Facebook is just such a pervasive part of their lives that it seems the first line of response if they need to communicate a message to others.

"I guess for these people the natural way to send a message out to their friends and others is via Facebook, unfortunately in this case the message was that they were stuck in a stormwater drain."

He warns that presents a real challenge for public education authorities to get their message across.

"Clearly it's not good enough to say 'well they should have rung emergency services', the point is that they didn't, and we need to think about why that's the case and what strategies can be used in the future," he said.