My cat keeps pooping in the bath tub...?

I've tried filling the bath tub with water but he just goes in it once it drains, He is about over a year old and he has been using the litter box for a year, but in September he started using the bath tub. I've been keeping the box clean but he still goes in there! Help?My cat keeps pooping in the bath tub...?
Just keep the bathroom door closedMy cat keeps pooping in the bath tub...?
If you really want this behavior to stop you can try this method I used it on my cat and it works and doesn't harm your cat. Clean the area (tub) with vinegar and then put a little on your finger and touch your cats nose and he won't like the vinegar and he won't poop where he smells the vinegar. The cat I had would poop in the closet and I did this and it worked. I hope this helps.
This may work for your cat: Put some mothballs in a couple of containers in the bathtub, this should dissuade him from going there at all. You will of course have to remove the containers to use the tub and then replace them.
Um, not to sound rude, but I would definitely NOT use that tub.





And I agree with the vinegar thing.