"Peter Duniho" wrote in message
...
"C J Campbell" wrote in message
...
Water can get into the system at any point, as you suggest.

As for waiting 10 to 15 minutes before sampling the fuel, why? Try this
experiment: put some water and some fuel in a jar. Shake it up, and time
how
long it takes for the water to settle out.

10 to 15 minutes might be overly generous, but your experiment doesn't
really duplicate the conditions within an aviation gas tank.

Some are lined with rubber bladders, that can get small wrinkles (or
sometimes large wrinkles, which is really bad) that hinder the flow of
water
toward the drains. Others have part of the wing structure inside the
tank,
with holes drilled at the bottom, that impede that flow. In ALL
wing-mounted tanks, water can be quite distant laterally from the drain,
and
it will take the water a lot longer to flow toward the drain along the
bottom than it would for water to be pulled by gravity straight down in a
jar.


Then why wouldn't you rock the wings to start out with? Make sure all the
water flows to the sump right away.