There is no real practical way to 100% waterproof a bathroom floor. You can use floor coverings that are waterproof but if the substrate isn't waterproofed it won't mean anything.
The trouble areas are toilet flanges, floor vents, doorways, wall/floor junctures, etc. They can all be addressed against water leaking through in one fashion or another but it depends on where the water is to come from, how much water is to come, and the duration of the wet condition.
The better bet is to keep the homeowners insurance premiums paid.