How do I start digging a tunnel under my toilet?

//ads -- adsterra.com -- native banner
?>
Prison Architect has just released their new escape mode. Its pretty cool, but I dont know how to start digging a tunnel. I find the wooden pick-axe, bring it back to my cell and left click. However, this only damages the toilet which eventually calls the guards. How do I dig under it instead of damaging it?
Pictures about "How do I start digging a tunnel under my toilet?"



How do you hand dig a tunnel?
Prisoners dig the shortest route to the building's exterior, then they continue digging until they meet the outermost fence or wall. If there's no external barrier, they will immediately dig upwards, exit the tunnel and attempt to escape.Plumbing Repair - DIY Tunneling Under a Slab Foundation
Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Ibrahim Boran, Julia Volk, Julia Volk, Bo Stevens