Put a step stool next to the toilet.
Naw, my cats already know how to get up on the seat and put their head down in the bowl and get a drink with a paw or two down to support them. Now if I could teach them to flush the toilet ... hey, that would give them a little more survival time, until maybe a relative (one of mine of course; both my boys were strays, so their relatives don’t know where they live) called several times and couldn’t get in touch.