Results on Google of a controlled experiment by MythBusters. They kept two untainted toothbrushes in an office far away from the lavatory and others in a loo. At the end of the month-long trial, they sent their toothbrush collection to a microbiologist for bacterial testing. Astonishingly, all the toothbrushes were speckled with microscopic fecal matter, including the ones that had never seen the inside of a bathroom. The confirmed myth unfortunately proved that there's indeed fecal matter on toothbrushes — and also everywhere else. I'm guessing there'll be a boom in toothbrush sales as the only way to prevent this deadly contamination is a new toothbrush every time we brush our teeth! I for one will continue to not give a damn!

I really like your herringbone tiles, am considering something similar so looking forward to more of your photos. I would go with painted behind the wall hung toilet as think it may get overwhelming with more tile. Where are your wall tiles from - they are a good combination of width and length?

The key element in adding loos is generally guided by the position of existing soil pipes.... unless you add a Maserati ( ah love auto correct - that can stay in !) a macerater ( saniflow or similar ) but most people don’t like the fallout when they get jammed ! So do you have an image showing next floor(s) up too? And are you thinking of extending out at any point ?

Build a wall with a door. No one wants a loo in their office.