For those worried about what might happen if robots take over the world, the experience of a security robot in Washington DC was reassuringly comforting for us humans after it came unstuck by something as simple as water.

The Knightscope K5 security robot was patrolling outside an office building the city's Georgetown area when it appears to have fallen into a waiting fountain.

The machine's pratfall garnered a wide response on social media.

"Steps are our best defence against the Robopocalypse" tweeted Peter W. Singer, along with pictures of the capsized machine.

Others joked on social media that that robot had decided to quit its job in the most dramatic way possible.

Another nearby Twitter user, Bilal Farooqui, wrote: "We were promised flying cars, instead we got suicidal robots." It prompted some to say the machine must be Marvin, the depressed robot from Douglas Adams' famous Hitchhiker's Guide to the Galaxy series.

Security robot in a DC fountain
Knightscope K5 after it's fall into a Georgetown fountainTwitter/S. Singer via Storyful

The Knightscope robot is lauded on its website as "cutting edge autonomous technology" - there's no mention of its ability to fight fountains.

It's not the first time a K5 has hit the headlines for something other than helping an area's security. Earlier in the year a drunk man was arrested after he knocked down the patrolling robot in California's tech hub of Silicon Valley.