You have nothing to worry about - I think I’ve seen your posts before and if I’m right, you were there not long after he actually had the sv right?
You didn’t catch it then so your chances of catching it now are literally nothing. I’ve never heard of viruses living in water, but think how often that toilet will have been used in 4 months so the water will have constantly changed etc, and no-one else has caught it. Try not to worry, I’m sure you will be just fine