The roommates in the girls' dormitory always squat on the toilet and always get toilet water on the toilet seat. I dare not sit on the toilet. What should I do?

Because of different living habits, maybe everyone is used to it and can't sit still. Maybe they are cleanliness addicts, and the toilet seat that everyone has sat on is unsanitary. However, in any case, it is her fault that she didn't clean up after squatting, which is a quality problem.

You can do it. If her defecation time is fixed, for example, after getting up every morning, you can queue up in front of her to go to the toilet, or you can take this opportunity to flush the toilet seat hard every night to keep it clean and hygienic.

Or when she is not in the dormitory, print an A4 piece of paper "Please clean the toilet in time after going to the toilet" and stick it on the wall in front of the toilet. First, when you write "everyone", you don't aim at her alone to reduce unnecessary contradictions. Second, serious people will understand and will not ask who did it. Once you get used to it, you don't need stickers.