Flying in the wet.
A good topic not normally touched.
A pitot cover will help prevent water getting into the pitot head, particularly driving rain from a storm.
When doing a sump test always fill the test tube FULL. Just taking a small sample could well be all water with no visible cut off line between water & fuel.
Several tests are better than one.
It can be wise to double check the fuel drains after a rain shower has passed. Water can and does get past even the best tank cap seals. Those seals are not getting any better with age.
When the sample has been taken then use the look, smell, add-water test to ensure it is OK. If in doubt then rock those wings and drain, drain and drain until you are 100% happy with the fuel in the tanks.
R16