Shaking a can with pennies or rocks in it is sooo much better than using a spray bottle. That is always my first recommendation. It is really not a good idea to teach your cat to fear water. If you ever have to bathe your cat (and there are countless reasons why you might have to) you will have a huge battle on your hands. Not all cats are afraid of the water during a bath, many cats actually enjoy the massage and warm water. But the ones that really panic and freak out usually have negative associations with it, either they fell into a toilet or a swimming pool, or they were sprayed with water from a bottle. The spray bottle method will certainly deter your cat from the bad behavior, but at such a high price. Please consider another alternative. As a professional cat groomer I can tell within seconds of bathing a cat whether they have had a traumatic experience with water. Upon speaking with the cats owner they usually reveal that they use spray bottles. I know I would certainly rather hear a loud noise than be hit with a spray of water - don't our cats deserve the same respect?