Putting on my Mr. Obvious hat for a moment: did you fill the bladder and taste the water before cleaning the bladder. That rules out that something you're using to clean it is reacting badly with the bladder. (I wouldn't think Bicarbonate would react, but like I said, Mr. Obvious here...)

I've never had any taste problems with Platypus, Nalgene Cantenes, or MSR Dromlite (mine are a few years old; I think they might use different materials now, so my MSR endorsement may be misleading for your needs.)