Throttle stock

I had some problems with the fail: throttle stock, and I found out that there was water/mud in my throttle body, I cleanded it, and changed the gas-cabel, and now it is running perfect again.
Does anyone now how the water can get in there, or have tryed it themselve?
My idea is that it comes in, when I clean the ATV with pressure washer, but im not sure :Thinkingof_:

Thanks, Lars