There is sealer for concrete, but standard sealer will deal with wet footprints, not a flood. There are also resin sealers, but they have other issues, including yellowing. I've seen polymerized concrete used for floors in places like daycare centers which was amazing. I don't know for sure, but I think it's probably close to impermeable. It's also more comfortable.

You can post this in the remodel forum and/or the bathroom forum.