did a little googling... found that in general a metallic taste can be related to
1. Very low pH water (3.0-5.5).
2. Heavy iron concentration in water above 3.0 ppm Fe.
3. Leaching of lead and copper
So in terms of fixing it... you're going to have to isolate what is causing the taste. Your water, silverware, dish detergent, cooking method, ??
good luck. hope someone is of more help than me!
(hopefully someone that's dealt with this problem?)