Protect model railway room from water

There is a washbasin where the supply line can break, a 200L boiler that can become leaky, a main water valve, a washing machine. Electricity and fire hazard were not my question.

Yes, a normal technical utility room basement. That is what my answer refers to, that more likely something else… man man man… could happen than a flood, provided you keep an eye on everything to ensure it is intact.

Sandbags are very impractical if I had to put them there every time.

You can leave them standing! You yourself write:

I am even willing to have to step over an 'obstacle'.

… so it is allowed to be impractical after all.

What would you do?

That is what I would do… that was your question.

Hello Jens, do you have a concrete suggestion of how or from what such a threshold could be made? Best regards

Hello Jens, do you have a concrete suggestion on how or what such a threshold could look like? Regards

Maybe something like sticking water stop thresholds for garage doors onto the floor.