bad tasting water

The water coming from the fresh water tank tastes like it came out of a plastic garden hose.  I use potable water grade hose from the camp spigot and an in line water filter.  The water (usually) tastes fine from the hose but ends up tasting like plastic from the r-pod kitchen spigot.  I've 'cloroxed' the fresh water tank and flushed several hundred gallons of water through it.  Any suggestion would be appreciated.