On my dishwasher I unscrew the big cap at the bottom of the machine and pour in about 500g (lb) of salt. The machine does not dispense it - it just runs the water through it until it's all dissolved - then, weeks later you put more in - you can not overfill the salt reservoir - not as long as you can still get the screw-on lid back on.
Peccavi, March 2010
