I tend to agree with CircusFan. It could be that s/he had her head in the waterbowl and what you hear is the sound of water from its cavities. However, it's better to be safe than sorry.
I had an animal treated for RI and the vet prescribed Baytril and Amakacin(sp?) via injections to the lower upper third muscule area near the dorsal, alternating sides per injection. He's doing well now but it could have been worse if I ignored the symptoms and did nothing.
In the meantime, increase the heat in the cage and try to increase the relative humidity as well. Clean the water dish/cage more frequently and keep the snake away from other animals in your collection. If it refuses to take a meal, do not offer the meal to any other snakes in your collection. These are preventative measures "just in case" your animal does in fact have have RI.
Hope this helps and good luck to you.