I had a very, very similar problem, but a different off-flavor.
I would recommend getting a water quality report for your tap or getting any analysis done on it. Just because you used bottle water doesn't mean anything. I tried that approach only to find out it was worse than my tap water.
Once you have the water report you can use any online calculator to see where you stand with your water.
If all else fails, use distilled water and 1 gram of gypsum, epsom salt and 2 grams of calcium chloride and stick to a smash pale ale recipe like Maris Otter with Cascade.