It's possible but not likely. I've never heard of an instance and would think it came from inside your house but I don't know. How a rat would get into the sanitary system would be one question. I guess larger cities than my half million might have unsecured openings. I hear new york city and florida stories about alligators.

You could call your sewer and/or environmental health department and get their opinions.

Are you going to be nervous to potty now?

I may be just from reading about it.

Rats which have been poisoned often will hop in toilet bowl to get a drink. I doubt he came up through the system. Set some traps out, he must have parents!

Yes I am. I haven't even told my Grandsons who live with me. It would scare them I am sure. Thanks for the quick reply Laurie