How can i stop cats using my front lawn as a toilet?

I have a problem with local cats using my garden as a toilet and want some tips on how to stop them. I have tried suggested tips like putting down orange peel or bleach but this does not deter them. I hate cats but i don't plan to kill any so please don't suggest poisons or anything like that. A friend recommended to me that apparently if i half fill a 2 litre empty bottle with water and put it near the spot where the mess occurs then this apparently works, have you heard of this? if so did it work for you, or do you have any other realistic non-expensive ideas.