Help!

My child is spending the night at my sister‘s house with her cousins. They were brushing their teeth and I was on FaceTime with them then my daughter showed me the sink which looked like it had stagnant old dirty water in it. I called my sister to ask her why was the sink like that and she said it’s been clogged for about two weeks. So all that stuff in there was Bacteria toilet paper make up from our oldest daughter and they wash their hands in there still .. my daughter said that the water might have gotten in her mouth now I’m nervous that she’s going to get some type of illness.