As for water jumps they are just part of the course. If you watch racing you will see horses who have fallen earlier will jump the water jump without their jockey. Because they enjoy it!
Horses would jump anything in their way as long as they don’t know what’s behind the obstacle. If there would be stones behind it, they would still jump it.
The fact that the water jump is much more dangerous than the normal fences is easy to understand. Ar Sandown the water in one of ten jumps, but statistically it causes more than the expected 10% in injuries.
The RSPCA does not seem to understand that horse racing is NOT cruelty.
In which other sports are you allowed to hit the main participant almost as much as you like and still keep the race?