There are a few different explanations as to water getting in your oil. Try doing a search here in the forums for 'water in the oil' or something like that. You'd be surprised how much that has been discussed on here. That along with the water pressure situation, is fairly common from what I've seen. I'm pretty new to jets myself, but I've gotten a lot of good info here on the boards and kinda helped myself along the way. Lots of good people here, though, you'll see