It was narrated from Kabshah bint Ka'b, who was married to one of the sons of Ab Qatadah, that:
She poured water for Abu Qatadah to perform ablution. A cat came and drank the water, and he tilted the vessel for it. She started looking at it (in surprise) and he said: "O daughter of my brother, do you find it strange? The RasoolAllah صلی اللہ علیہ وسلم said: 'They (cats) are not impure, they are of those who go around among you.'"
[Ibn Majah 101 sanad sahih]
Rasool صلی اللہ علیہ وسلم also said:
يُغْسَلُ الإِنَاءُ إِذَا وَلَغَ فِيهِ الْكَلْبُ سَبْعَ مَرَّاتٍ أُولاَهُنَّ أَوْ أُخْرَاهُنَّ بِالتُّرَابِ وَإِذَا وَلَغَتْ فِيهِ الْهِرَّةُ غُسِلَ مَرَّةً
Wash the vessel the dog has drunk from seven times: the first or the last of them with dirt. And when the cat drinks out of it, wash it once.
[Jami at Tirmidhi 91 Sunan Daraqutni 1/64]
This proves that we should also avoid to drink or eat from the same utensils from which a cat has eaten or drank.
