So let me ask an indelicate question: why did the dealer say I had water in the fuel and propose between $700 and $4700 in repairs? I realize that you're not psychic, and I won't hold you to your answer. It sure seems to me like, "water in fuel" vs "no water in fuel" is pretty cut-and-dried, but maybe it isn't. Maybe one sample can have water and another sample won't.
The thing is, I have no experience in this area, but I do have experience as an expert who troubleshoots complex systems. I know that there are times when an expert can make a reasonable diagnosis that turns out to be wrong, because things aren't always cut-and-dried in the real world. At the same time, I know that there are times when an expert can make a plausible diagnosis that results in lots of charges to the customer, and is reasonably defensible if it turns out to be wrong later. And, of course, there are also cases of out-and-out fraud. If the dealer is right, and there was water in my fuel, I need to figure out how it got there and take appropriate steps to remediate. But the engine runs fine once it starts, I changed my filter about 10k miles ago, and there was no water in the sample that I pulled from the filter. So what's up?