Is betta water a biohazard?

I bought a heater for my new betta and made a mistake when applying it to the tank (a part of it was sticking out) so I had to pull it out and subsequently, some water splashed on the floor which really upset my roommate. He went on to tell me that fish water is unsanitary and a biohazard and that I should probably move the tank outside.

I don't want to move my betta outside because even with the lid on the tank, I'm afraid that raccoons or cats could get inside and the weather where I live is unpredictable. I use basic disinfecting wipes to clean up spills, but is there more I should be doing or is this just a misunderstanding?