The main point is that punishing your cat (with water or anything else) AFTER the fact is totally useless because they don’t make the association between the act and the punishment. We make that association but the animal does not. They are totally confused as to why this negative action is happening to them. They just see it as random cruelty.
Cats are normally so fastidious. If he’s doing this after 10 yrs of no bathroom problems, this is a SIGNAL that something is WRONG.
They can’t talk so it’s up to us to figure out what’s going on. The most common is some sort of physical or medical problem.
The first step is a Vet visit and a thorough checkup. If that yields nothing, then your Vet can guide you as to what else to try. But in all likelihood it is something physical (whether bladder related or not)
I’ll just give you one brief example (I’m not saying it’s the case with your cat).
I was a live in caregiver for an elderly couple with a cat. Everything was fine with the cat for more than a year.
But one day he peed in a box sitting in a corner. He had also run out of the house several days before. But the peeing out of his box was my signal to get him to the Vet ASAP.
One of the things she did was to pass a fine tooth comb through his fur and the exam table was absolutely covered in flea dirt, he was that severely infested.
After a course of Frontline and thorough cleaning everything returned to normal.
You may wonder what the connection was between peeing outside the box and having a severe case of fleas. Obviously not a direct connection. But this was his way of signaling that SOMETHING was very very wrong.
It’s our job (with the aid of the Vet) to interpret what the signals mean. Something is bothering your cat. It’s not like he just up and decided to pee on the floor just to spite you or something.
Something is wrong. Hopefully it will be something physical with a straightforward solution. Or it may take a little more sleuthing. But it’s not happening for no reason at all or cause he just doesn’t like you anymore or purposely wants to be disobedient.
He can’t talk but he is sending you a signal. You just need to figure out what it means. The logical first move is the Vets office.