I had the same problem. There is definitely a known problem with these units as evidenced by reviews on Amazon and epinions. My first unit leaked terribly after using it twice. I returned it and got a second unit. If you do not put the clean water container in just so, it does something to the valve and causes it to leak. Sometimes it goes in perfectly and sometimes it doesn't. This is unacceptable in my opinion for a unit of this price. If it's under warranty, try to see what a repair person can do and definitely tell Eureka that you are unhappy with the unit's quality. It's not you, it's a poor execution by Eureka of what could have been a great machine.
T Collins
January 2007