Keep draining until you don't. Pretty common when there's a fog and you get condensate. The tank on a small airplane isn't gonna be sealed air-tight, it's ven

Keep draining until you don't. Pretty common when there's a fog and you get condensate. The tank on a small airplane isn't gonna be sealed air-tight, it's vented to the outside air so a little condensate is pretty normal. Water is heavier than the gas, so it sinks to the bottom where the drain fitting is.