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this can be a problem, removing the tank and flushing it would be the only real way of getting all of the dirt, replacing the tank is a better option, you don't want to flush it while its in the refrigerator because you will get the dirt into all the lines and possibly clog them, you can order a new one @ http://www.repairclinic.com/SSPartDetail.aspx?s=t-ZISS48DASS-%3d%3dpi294478&PartID=294478 if you wish, thanks Bryan
I had found that part online, altho at a different website. http://www.appliancepartspros.com/part_details.aspx?part_id=2065450&image=0
Is replacing the water tank a task that the relatively handy homeowner is capable of doing themselves? And if yes, what is involved besides turning off the water? Any tricks to separating and reattaching the plastic lines at go in and out of the water tank?