YOU SAID:

I put my hand inside a toilet.

INTO JAPANESE

私はトイレに手を入れました。

BACK INTO ENGLISH

I put my hand in the toilet.

INTO JAPANESE

トイレに手を入れた。

BACK INTO ENGLISH

I put my hand in the bathroom.

INTO JAPANESE

浴室に手を入れた。

BACK INTO ENGLISH

I put my hand in the bathroom.