A recent off-field landing in a Long-EZ, fortunately with no injuries, forcibly brought to mind the ritual of checking for water at all the drains. A standard Long-EZ has a gascolator drain on the firewall which should be easily accessible through the cowling inlet. This should be drained before each flight, once the airplane is in the level position (on all three wheels). There is a water drain at the forward end of each main fuel tank and these must be drained before each flight but before the airplane is moved. That is to say, while it is parked in the normal nose down position. Do not lift the plane up to the 3-point position until after you have checked these two water drains. If you are in the habit of normally parking your EZ in the level, 3-point position (tying the nose down), you should consider installing low point water drains in each sump blister and then check them religiously before every flight.
Where does the water come from? Sometimes, but rarely, from the gas pump (or gas truck), very rarely, if ever in a composite EZ-type, from condensation in a less than full fuel tank. This is common in metal airplanes. That is why it is normal to top off the tanks in any Spam Can after a flight. Because the fuel tanks in any RAF design are insulated sandwich construction, they are similar to a thermos bottle and condensation does not normally form on the inside of our fuel tanks. The most likely way for water to get into your fuel tanks is a leaking fuel cap on an airplane left out in the rain.
The "O" rings on any of the commonly used fuel caps do not last forever. Far from it, in fact. Ozone, ultra violet light and many airborne pollutants attack these rubber "O" rings. Check them frequently and replace them as soon as you see small cracks in the outer edges of these "O" rings. Be especially diligent about checking your water drains if you have left your airplane out in the rain. Also, if you fly into an airport on one fuel tank with no problems, consider taking off and climbing to a safe altitude on that same, known to be free of water, fuel tank. Switch to the other (unknown) tank only after you have plenty of altitude to allow a safe return to the airport in the event water may be in this fuel tank. This philosophy is an old one but a good one. For the same reason, if anything untoward happens when you switch tanks, always switch back to the first tank before you try anything else.