i have a 2006 f550 water in fuel light keeps coming on. we have replaced fuel filters but not able to get it to go away. is there a place to drain the water. where is the sensor.

 

It's on the fuel pump mounted on the frame rail.

 

You can try to remove the drain plug ( hex keyed plug towards the bottom of the cover) and squirt carb cleaner in there to flush it out. In the picture it is slightly hidden behind the fuel heater wire. If you still have issues then I'd remove the cover and see if it is gunked up.
. This is also where the primary fuel filter is. Only use Motorcraft filters because the primary has a water membrane where many aftermarket don't.

 

It's on one of our grass fire trucks I live in western Kansas and we been having fires allnost daily I drained no water so when things cool off around here will check more into it

 

Fyi I have the same issue on my '06 (130K miles). I bought a genuine Ford sensor on Amazon for $24 but have yet to change it out. I read that changing the sensor should solve the issue.

 

More than likely, the chamber that the w.i.f. sensor screws into is filled with a gelled-up mixture of dirty fuel/dirt like 87CrewDually said. It's easiest to just remove the housing off the frame and take it apart to clean it out. You will be amazed at how much crap is in there. I just went through this a few months ago on my '06, the w.i.f. light kept coming on no matter how often I drained it. After I cleaned it out, the light has not come back on. Some will say the gasket for the side cover can't be reused because it distorts once you open it up. Mine popped out of the channel it sits in and would not go back in. I took it out and put it in my freezer for 15-20 minutes and it contracted back to it's original size. Hasn't leaked a drop since the re-install.