Aḥsana Allāhu ilaykum. My cat fell into the toilet, but I did not see any visible najāsah, such as urine or feces, in the toilet. However, there was a red stain around the toilet. Is the water considered najis?

Ustadh AbdulAziz al-Haqqan

Red stain, stain of what? If you wanted to wash the cat, you can wash the cat; that's not a problem. Why is this even a question, Barakallahu fiik?